用咖啡因优化身心表现

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我是安德鲁·休伯曼，斯坦福大学医学院神经生物学与眼科学教授。今天我们要讨论咖啡因。

咖啡因是地球上使用最广泛的物质之一。据估计，超过 90% 的成年人，以及多达 50% 的儿童，也就是青少年和十几岁的年轻人，每天都摄入咖啡因。咖啡因是一种奇妙的分子。

大多数人都知道咖啡因能够提高警觉性，减轻困倦和疲劳感。它确实能做到这一点。但大多数人没有意识到的是，咖啡因还具有很强的强化作用。

我所说的强化作用是指：当饮料或食物中含有咖啡因时——而且确实有许多食物含有咖啡因，只是我们并不知道——我们会逐渐比不含咖啡因时更喜欢这些食物和饮料。因此，它会强化我们对某些食物和饮料的喜爱。事实上，它甚至会强化我们对盛放这些食物和饮料的容器，以及与我们一起摄入含咖啡因食物和饮料的人的喜爱。

也就是说，咖啡因不只是一种兴奋剂，咖啡因还是一种强化剂，而且它在几乎每个人的日常生活中都发挥着积极作用。我们可以有把握地这样说，因为正如我刚才提到的，超过 90% 的人都在摄入咖啡因。大多数人以为自己摄入咖啡因，是因为它让自己更加警觉。

但人们摄入咖啡因还有很多原因。我不会告诉你摄入咖啡因一定有害。事实上，今天我会介绍咖啡因的许多积极健康作用，包括神经保护作用、抗抑郁作用，以及对心理表现和身体表现的提升作用。

话虽如此，在某些情况下你会希望避免咖啡因，也有一些人可能会选择不摄入咖啡因。尤其是当我们不只把咖啡因看成兴奋剂，还把它看成强化剂时，更应该注意这一点。咖啡因的强化作用非常强，即使某些食物和饮料中只含有极少量咖啡因，你也会很快开始偏爱这些食物和饮料，而不是其他选择。这究竟是好是坏，取决于你想做出什么样的食物和饮料选择。

所以今天我会从机制层面说明咖啡因如何发挥作用。我保证尽量少用术语，即使你没有生物学背景，也能轻松理解这些信息。然后我会告诉你如何利用咖啡因，或者反过来，如何在某些时候避开咖啡因，从而让它为你所用。

今天这期节目既会讨论机制，也会讨论工具，也就是如何使用和利用咖啡因来改善心理健康、身体健康和表现。在继续讨论之前，我想先讲讲一种存在于某些含咖啡因饮料中的分子。事实证明，这种分子对减重、心理表现和控制血糖都很有帮助。它就是 GLP-1，即胰高血糖素样肽-1。

胰高血糖素样肽-1 存在于大脑和身体中，同时作用于大脑与身体。它能做很多不同的事情，但目前发现的主要作用之一是降低饥饿感，而且它通过两种方式做到这一点。

它会激活下丘脑中的某些神经元。下丘脑是控制饥饿和饱腹感的大脑区域。它能在大脑层面让我们感到吃饱了，也就是产生饱足感。事实证明，GLP-1 还会作用于肠道中的某些受体，让我们产生已经摄入足够食物的感觉。

它不一定让我们觉得肠胃被撑大了，但会让我们感到饱。这很有意思，因为你想想看，我们进食时，胃显然会被填满。这个信息必须传递给大脑，大脑才能发出饱腹信号，真正关闭饥饿感。你可能难以相信，胃部充满时，大脑甚至会启动信号，降低我们继续咀嚼的欲望。

正如我刚才提到的，GLP-1 会作用于大脑，产生已经吃够了的饱腹感，并降低我们继续进食的欲望。GLP-1 也会直接作用于肠道，让我们在肠道中产生轻微的充盈感，再把这个信息传给大脑。因此，当体内存在 GLP-1 时，实际上会同时发送两种并行信号。

这里简单讲一点与 GLP-1 有关的历史。它最初是在希拉毒蜥身上发现的。这种爬行动物可以长时间不进食。一位非常聪明的科学家决定研究，为什么像希拉毒蜥这样的动物能够长时间不摄入任何东西。原因在于，它们会产生大量 GLP-1。

研究人员从中分离出了这种肽，然后寻找人类体内相应的肽。结果发现，人类确实也有类似的肽。正如我所说，它会在大脑和身体中释放，让你产生饱腹感。为什么我要告诉你这些？因为今天我们要讨论咖啡因。

有一种特别的咖啡因来源是马黛茶，另外还有一些与马黛茶相似的茶，也会显著刺激 GLP-1 的释放。如今还有一类药物，被称为 GLP-1 类似物。这些药物会模拟，或者与人体产生的 GLP-1 相同。事实证明，这些药物对治疗某些类型的糖尿病和肥胖非常有效，但它们会大幅激活 GLP-1 通路。

对于确实在努力减重的人来说，这些属于比较极端的情况。不过，目前针对普通人群的临床试验和数据表明，GLP-1 类似物非常有前景。马黛茶只要不是烟熏品种就可以——我之所以特别说明这一点，是因为有不少人提醒我，马黛茶有烟熏和非烟熏两种，而烟熏品种被认为可能具有致癌性，也就是可能促进癌症发生。

因此，我建议大家避免烟熏马黛茶。但众所周知，马黛茶会显著促进 GLP-1 释放，所以主要通过抑制食欲，可能成为一种有效的减重工具。再次强调，它既在大脑层面发挥作用，也在肠道层面发挥作用。我刚才讲的这些已经为人所知一段时间了，但最近发表在 Cell Press 旗下优秀期刊《Cell Reports Medicine》上的一组新发现，准确说明了 GLP-1 如何促进饱腹感，以及如何通过其他机制带来额外减重。

我觉得这个机制非常有意思，也确实很重要，因为我们之前在节目中讨论过一些相关主题。基本发现是，无论 GLP-1 是通过处方类似物释放，还是通过饮用马黛茶等方式刺激身体释放所谓的内源性 GLP-1，它确实会在大脑和身体层面让你更有饱腹感。但事实证明，它还会刺激产热。

产热是指主动利用更多代谢能量。尤其是所谓的米色脂肪细胞和棕色脂肪细胞，它们是身体中产热活动的重要来源。基本情况是，你有白色脂肪细胞，也就是白脂肪；你还有米色脂肪细胞和棕色脂肪细胞。

米色和棕色脂肪细胞是我们确实希望拥有更多的脂肪细胞。它们并不大量存在于皮下，而是主要集中在锁骨周围和颈部上方。它们负责产热。它们呈现米色和棕色，实际上是因为这些细胞中含有大量线粒体。

当体内 GLP-1 水平升高时，它会向那些白色脂肪细胞传递信号，帮助它们转化为米色和棕色脂肪细胞。也就是说，它会把原本除了储存能量之外没有太多作用的脂肪细胞转变过来。我想，大多数人都希望减少这类白色脂肪细胞。确实有少数人太瘦、太单薄，可能需要更多脂肪，但大多数人苦恼的是白色脂肪细胞过多。

当你摄入马黛茶、服用 GLP-1 类似物，或通过其他方式刺激 GLP-1 时，除了增强饱腹感，也会刺激白色脂肪细胞转化为米色和棕色脂肪细胞。这会提高产热能力，随着时间推移提高基础代谢率。这样一来，即使在静息状态下，你也会燃烧更多热量；在静息时，你也会感觉自己更能适应寒冷环境。

这与洗冷水澡、定期冰浴或经常进入冷水时诱发的机制非常相似。冷刺激同样会促进白色脂肪细胞转化为米色和棕色脂肪细胞。我很喜欢这些发现，因为它们提供了机制上的一致性，也为 GLP-1 为什么可能如此有效地帮助减重，提供了一个很好的解释。

一方面，GLP-1 会降低食欲，这当然能帮助人们维持体重或减重。另一方面，它还会提高基础代谢率。现在我们知道，这至少可能部分通过这样一种机制实现：它促进那些除了储存能量之外作用有限的白色脂肪细胞，转化为富含线粒体、具有代谢活性的米色和棕色脂肪细胞。你可以把它想象成蜡烛中的燃油，让你的代谢炉以更高的温度和更快的速度燃烧。

这就是其中的机制。工具层面的基本结论是，如果你想减重并利用 GLP-1 通路，那么在一天早些时候喝一两杯马黛茶，是刺激 GLP-1 释放的好方法。还有其他刺激 GLP-1 释放的办法，比如某些形式的运动，尤其是空腹运动。

这实际上支持空腹运动。人们一直争论空腹有氧运动是否比非空腹有氧运动燃烧更多脂肪，数据基本表明并非如此，二者并没有真正差别。但这种说法没有充分考虑 GLP-1 释放等因素在更长时间尺度上的影响，所以这一点也需要纳入考虑。因此，你可以进行空腹有氧运动。

你也可以喝马黛茶，但要记住马黛茶含有咖啡因。之后我们会进一步讨论马黛茶中包括咖啡因在内的具体兴奋性成分。不过，马黛茶是刺激 GLP-1 释放的好方法。当然，如果你希望更强地激活 GLP-1，也许可以考虑目前已经出现的一些处方 GLP-1 类似物。

当然，那是更强烈的 GLP-1 刺激。无论你是想减重、增重还是维持体重，我认为在不久的将来，我们都会更多听到 GLP-1 类似物，以及能够刺激 GLP-1 的饮料和补充剂，因为它看起来确实是一种非常重要的生物学机制。

在开始之前，我想强调，这档播客与我在斯坦福大学的教学和研究工作彼此独立。不过，它确实体现了我向公众提供免费科学及科学相关工具信息的愿望和努力。秉持这一理念，我要感谢今天节目的赞助商。

第一位赞助商是 Levels。Levels 是一项服务，它通过连续血糖监测仪，实时反馈饮食对健康的影响，让你了解不同食物如何影响自己的健康。血糖，也就是血液中的葡萄糖，是影响即时和长期健康的关键因素，也会影响你在任何时刻的活力、思维清晰度和整体状态。

关键之一，是了解不同食物、食物组合以及进食时间如何影响血糖。使用 Levels，你可以实时评估这些因素。我体验过 Levels，它让我发现，例如，我在一天中的某些时段可以吃某些食物，但如果在其他时段吃，就会出现血糖骤降。

它还让我了解如何安排运动和进食的间隔。事实证明，对我来说，空腹运动更有益。这是我通过 Levels 学到的东西，它彻底改变了我的饮食与运动安排，以及桑拿等活动的使用时间。这是一次非常重要的学习经历，改变了我生活中的大量因素，让我感觉更有活力，心理专注度更高，身体力量和耐力也更好。

如果你想进一步了解 Levels，或者亲自尝试连续血糖监测仪，请访问 levels.link/huberman。再说一次，网址是 levels.link/huberman。

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Let's talk 关于 caffeine. So as I mentioned earlier, caffeine is consumed by basically most all adults every single 天 和 consumed at 非常 regular times each 天. In fact, if 你 were to take a look at 你的 caffeine intake 或 the caffeine intake of somebody close to 你, what 你 会 realize is 那 they don't do so well if their caffeine intake arrives even 10, 20, 或 30 分钟 past their expected 或 usual intake of caffeine. 那's pretty remarkable, 和 it brings to 心智 ideas 那 我们 are all, quote unquote, "addicted to caffeine" 或 那 caffeine is somehow bad.

I'm certainly not going to make the argument 那 caffeine is bad. 首先 of all, I'm a regular caffeine user. I wouldn't call myself a caffeine abuser, 但 I am a regular caffeine user. 和 caffeine is known to have certain health benefits. I listed off a few of them earlier, 但 I'll mention 那些 again now 之前 going forward.

Caffeine is known to have certain neuroprotective effects. 和 那 is 因为 of its ability to 增加 neuromodulators, such as 多巴胺, 但 also other so-called catecholamines like 去甲肾上腺素. If 你 don't know what 那些 names mean, 这些 are molecules 那 增加 水平 of alertness, motivation, 和 drive. 和 so then 因此 not surprisingly the large scale analyses of the relationship between depression 和 caffeine shows 那, provided 人们 are not drinking so much caffeine, 那 it makes them overly anxious, 那 regular intake of caffeine is inversely related to 水平 of depression.

So it may have some antidepressant effects. 和 那些 could be direct 或 indirect. What do I mean by 那? Well, 你 可以 imagine 那 if 人们 are ingesting caffeine 和 they are 更多 motivated to do work 和 pursue quality social interactions, then the probability 那 they 会 have depression could be lower. It could also be 那 there are direct effects on the chemical 系统 of the 大脑 那 relate to 情绪 和 well-being 那 could offset depression.

It is not clear whether 或 not the effects of caffeine in countering depression are direct 或 indirect. Nonetheless, there's a relationship there, 和 it's an interesting 和 positive 一. 或 I 应该 say negative correlation, positive effect overall on 情绪 和 well-being, to be exact.

Now it's also the case 那 caffeine 可以 改善 心理表现 和 身体表现. 这 has been demonstrated in tens of thousands of 研究. I 会 review a few 研究 on 这, in particular, today. 但 to just give 你 a sense of how caffeine works at the 水平 of its timing 和 impact on 心理表现 和 身体表现, when 我们 ingest caffeine, provided 那 我们 don't have a lot of food in 我们的 stomach 和 那 我们的 血液 sugar isn't particularly high, generally, 我们 experience an 增加 in alertness within 关于 five 分钟.

和 那 增加 in 专注 和 alertness peaks 大约 30 分钟 之后 ingestion of caffeine 和 persists 对于 as long as 60 分钟. Now 这 is assuming 那 一 takes caffeine in pill form 或 drinks the entire caffeine drink within a short period of time. 但 a little bit later, I'll talk 关于 how 你 可以 consume caffeine at regular intervals while doing mental work 或 physical work in a way 那 可以 further 增加 心理表现 和 身体表现.

但 let's just touch on what caffeine intake 确实 does 对于 心理表现 和 身体表现. Perhaps the most robust finding across all of the 研究 那 I've examined is 那 caffeine 减少 我们的 reaction time. 那 is, it 改善 我们的 reaction time. It doesn't make it longer. It makes it shorter.

So 对于 instance, in a laboratory 研究 where 人们 were asked to hit a lever every time they hear a tone, 你 可以 greatly 减少 the time between the tone 和 the pressing of the lever if 人们 ingest caffeine 关于 30 分钟 之前 they do 那 task. Now 那 seems like a trivial task, 但 这 is also seen in the domain of sports 表现 和 even in cognitive 表现, where 人们 have to arrive at a particular answer to a question. 和 the answer to 那 question has to be pulled 从 their memory banks within their 大脑, their hippocampus, 对于 instance, a 大脑 structure involved in memory.

和 if 你 are asking 人们, 对于 instance, to remember the capitals of 不同的 states 或 cities 或 to remember certain historical facts, they 会 do 那 at a particular rate. 但 if they've ingested caffeine within the 小时 prior, their ability to recall 那 information is much, much better. They are faster, 和 it does not appear 那 accuracy is reduced.

In fact, in many cases, accuracy is enhanced. 和 那's 因为 caffeine both works on the reaction time 系统 of the 大脑和身体. I'll talk 关于 the mechanisms 对于 那 in a little bit.

但 it also stimulates certain 神经递质 和 so-called neuromodulators within the 大脑和身体 那 give the neural 回路 in the 大脑 那 are associated 与 learning 和 memory a lower threshold to activation. What does 那 mean? 那 means 那 我们 are better able to access the 大脑 circuitry involved in learning 和 memory when 我们 have a certain amount of caffeine circulating in 我们的 系统.

So 这 makes caffeine an incredible 表现-增强 compound. 和 I could give 你 tens of thousands of examples of 这 in humans. 但 之前 I do 那, I want to just touch on what 我们 know 关于 the existence of caffeine in nature 和 what the existence of caffeine in nature 和 its effects on other animals tells us 关于 what caffeine does in humans. 因为 as I alluded to earlier, what caffeine is doing 对于 us is not just making us 更多 alert, improving 我们的 memory, improving 我们的 reaction time, 和 so on.

It's actually acting as a powerful reinforcer of experience. 和 it's acting as not just a powerful reinforcer of the caffeine-containing drink 那 我们 drink 但 also the mug 那 it's contained in, plus the person 那 我们 可能 be sitting across 从 when 我们 consume 那 caffeine, 和 so on 和 so forth. If it's a little bit hard 对于 你 to conceptualize what a reinforcer is 和 why I'm calling it a reinforcer, let me spell it out in 三 具体的 ways.

我们 经常 hear 关于 the word reward, 和 我们 think, OK, if 我们 do certain things 和 我们 like the outcome, then 那些 certain things are rewarded. Right? If 我们're doing something, 我们 receive praise. The praise is the reward. 和 因此, 我们 are 更多 可能 to do 那 thing in the future.

In fact, a lot of parenting is like 那. 和 a lot of life is like 那. 然而, when 我们 hear the word reward, 我们 经常 think 关于 something 那 feels good to us. 和 certainly, if 我们've worked hard 和 我们 get some praise, 那's natural 对于 the praise to feel good to us.

或 对于 instance, if 我们 work 非常 hard 和 我们 get a certain outcome-- a trophy, a financial outcome, a degree outcome, recognition, et cetera-- all of 那些 可以 act as rewards, 但 那些 are all conscious rewards. 我们 are aware 那 they are happening. Reinforcers are a little bit 不同的 因为 the word reinforcement 可以 apply to conscious rewards of the sort 那 I just described, 但 there are also many ways in which caffeine stimulates the 释放 of chemicals in 我们的 身体 那 act as reinforcers.

但 那些 reinforcers are subconscious. 那 is, 我们 are not aware 那 they cause 这 preference 对于 the activities 那 cause their 释放. So the 研究 I'm 关于 to describe beautifully, I believe, encapsulates how is it 那 humans came to consume caffeine 和 why caffeine exists in nature 和 the powerful effects of caffeine as a reinforcing agent both in animals, insects, 和 in 你 和 me.

和 the title of the paper is "Caffeine 和 floral nectar 增强 a pollinator's memory of reward." Keep in 心智 那 caffeine is made 从 plants. Some of 你 会 say, duh, 但 I think some of us don't realize 那 the reason why there is caffeine in coffee is 因为 coffee comes 从 a plant. It's a coffee bean, certain teas, which, of course, are plants 那 人们 brew.

Caffeine is contained in 那些 teas, such as yerba maté. Well, why 会 这 bitter substance-- 因为, in fact, caffeine is quite bitter in high concentrations. Why 会 这 bitter substance be something 那 insects 或 animals 会 want to consume at all? It turns out 那, in most plants, caffeine is present in small enough quantities 那 insects 和 other animals-- 和 in fact, 我们 可以't actually taste the caffeine.

If I were to give 你 a little bit of pure caffeine, yes, it 会 be a stimulant 对于 你, 但 你 会 say 那 it tasted awful. It's in a category of compounds 那 会 strongly stimulate the bitter 受体 on 你的 tongue 和 会 make 你 cringe 和 pucker 和 本质上 walk away 从 whatever it is 那 contain 那 caffeine 和 从 the experience 那 contain 那 caffeine. Well, in nature, caffeine is present in 非常 low concentrations 或 is masked by other flavors within flowers, beans, 和 plants.

和 what 这 paper 确实 points to is 那 caffeine in nature is acting as a reinforcer 对于 bees 那 are consuming 不同的 nectar. So the way 那 it works is 那 bees, of course, go 从 flower to flower, 和 they are consuming the nectar. They are bringing nectar 和 pollen back to the hive, 和 那 provides critical nourishment 对于 the bee colony.

The bees are foraging in a way 那 includes information 关于 color, in particular, ultraviolet color, things 那 我们 可以't see 但 they 可以 see, 因为 they have 不同的 photoreceptors than 我们 do. 和 what the 研究 shows is 那 plants 和 nectars 那 contain 非常 small amounts of caffeine are the preferred sources of food 对于 bees. 和 the 研究 is beautiful 因为 they were able to confirm 那 they could mask the caffeine taste.

So they know 那 the bees are not preferring the taste of caffeine. 但 what they do is they pair caffeine 与 不同的 food sources 对于 the bees, then they remove the caffeine. 和 what they find is 那 the bees 非常 strongly prefer flavors 那 contain caffeine, not 因为 they could taste the caffeine 但 rather 对于 the way 那 那些 caffeine-containing flavors made the bees feel.

So how do 那些 caffeine-containing flavors make the bees feel? The same way 那 they make 你 和 I feel, a little bit 更多 alert 和 thereby able to do 更多 work. 对于 the bee, the 更多 work is the consumption of 更多 food, which then has a further reinforcing effect. So what 我们're 确实 talking 关于 here is the fact 那 A, caffeine exists in nature, in plants. It exists in concentrations 那 are 非常 low, so low, in fact, 那 they are not detectable to the taste 受体 of insects, 和, in many cases, to the taste 受体 of humans.

和, of course, there 可以 be high 水平 of caffeine in a plant. 但 if the plant also contains compounds 那 mask the flavor of caffeine, well then, 那些 plants are going to 本质上 be even stronger reinforcers 对于 the flavor of the plant, OK? So now 我们're talking 关于 strong flavors plus strong neurostimulant effects of caffeine.

和 the most 重要 point here is 那 all of 这些 effects of caffeine are subconscious. It is not 因为 the bee 或 你 likes the taste of caffeine. In fact, most 人们, when they take their 首先 sip of coffee, they find it taste bitter 和 kind of noxious. They don't like it. 你 may not even remember 那 因为 it happened so long ago 和 因为 caffeine is such a strong reinforcer 那 非常 quickly 你 come to like the taste of coffee.

你 可能 even come to like the feeling of 你的 mug in 你的 hand. 你 可能 even come to like the smell of coffee 和 so on 和 so forth. 和 那's 因为 caffeine stimulates the 释放 of certain 神经化学物质 in the 大脑, in particular, 多巴胺 和 acetylcholine, 二 neuromodulators 那 增加 我们的 专注 和 alertness 和 我们的 feelings of well-being.

A little bit later, I'll tell 你 那 caffeine stimulates the 释放 of 多巴胺 in a way 那's 非常 much distinct 从 the classical 多巴胺 通路 associated 与 addiction 和 reward. In fact, 我们 可以 think of caffeine as having a somewhat privileged access to the reward 系统. I'll give 你 a bit of a hint of where 这 is going.

Caffeine stimulates the 释放 of 多巴胺 和 acetylcholine not within the classic so-called mesolimbic reward 通路. 那's just fancy nerd speak 对于 the reward 通路 of the 大脑. They're associated 与 things like sex 和 food 和 drugs of abuse, like cocaine 和 methamphetamine. 但 rather, caffeine seems to stimulate the 释放 of 多巴胺 in the parts of the 大脑 那 are associated 与 alertness 和 cognition, meaning the forebrain. 这 is 非常 重要.

我们 have multiple 多巴胺 系统 in the 大脑和身体, 和 caffeine seems to stimulate 多巴胺 directly within the components of the 大脑 那 are associated 与 clarity of thought 和 well-being, 但 更多 so clarity of thought. Now, I'm also talking 关于 caffeine as a strong reinforcer in 那 it makes 你 feel good overall. 和 it does.

和 那 suggests 那 it also taps 进入 the 更多 classic reward 通路. 但 it does 那 in a 非常 interesting 和 frankly almost diabolical way. When 我们 regularly ingest caffeine, it stimulates the 增加 in 多巴胺 受体 at multiple sites throughout the 大脑 但, in particular, within the reward 通路 of the 大脑. So not the areas of the 大脑 那 are associated 与 专注 和 clarity of thought 和 cognition.

It does 那, 但 it is also increasing the 水平 of 多巴胺 受体 in the reward 通路. 和 what 那 means is 那, 对于 any 多巴胺 那's 释放了 in response to a positive experience, social experience, 或 any number of the other things 那 可以 stimulate 多巴胺 释放, there are 更多 受体, 更多 parking spots, if 你 会, 对于 那 多巴胺 to arrive at 和 to exert its 增加 in 情绪, 增加 in motivation, 和 overall feelings of drive 和 excitement. So there are four ways 那 caffeine works 那 我们 need to understand.

首先 of all, caffeine acts as a reinforcing agent. It 增加 the probability 那 你 会 return to 和 engage in a certain activity 或 consume a certain beverage 或 food. 秒 of all, caffeine 增加 多巴胺 和 acetylcholine, which are both neuromodulators in the forebrain, which helps us 改善 我们的 ability to think, to modify 我们的 rule sets. 那 is, to adjust 我们的 strategies 对于 不同的 social situations 和 mental demands 和 physical demands.

和 third, it 增加 the number 和 efficacy of 多巴胺 受体 in the reward 通路 of the 大脑. 那 is, it makes things 那 会 feel pretty good feel even better. 和 fourth, caffeine acts as an antagonist to adenosine, which offsets the sleepiness 那 我们 会 otherwise feel 从 the accumulation of adenosine 那 occurs as 我们 are awake 对于 更多 和 更多 小时 throughout the 天.

So let's talk 首先 关于 caffeine as a reinforcing agent. Again, 这 was 首先 most beautifully demonstrated in 这 研究 on honeybees where the bees prefer nectars 那 contain caffeine. 和 那 all makes perfect sense in terms of the ecology of bees 和 flowers 那 contain nectar.

There's an advantage, at least in terms of adaptation, 那 the flower benefits 因为 of distribution of things 从 the flower, which is good 对于 the flowers 和 the bees benefit, 因为 they're getting food. 和 so there's a kind of a symbiosis there. 但 与 humans, 我们're consuming caffeine-containing beverages 对于 我们的 sake. I don't think 我们 have it in 心智, nor do the bees have it in 心智, frankly, 那 我们're trying to preserve the plants 那 provide the caffeine.

I think 我们 会 all suffer, 或 I 应该 say 90% of adults 会 suffer greatly if all the caffeine-containing coffee 和 tea plants were gone, certainly. 但 most of us are not consuming coffees 和 teas 和 caffeine-containing foods 因为 我们're thinking 关于 the plants they come 从 和 我们 want to help 那些 plants. 我们're thinking 关于 how 我们 want to help ourselves. 和 yet the point of the reinforcing effects of caffeine are 那 they are largely subconscious.

我们 are not aware of them. Now 你 可能 say, no, 那's not true. When I drink caffeine, it makes me feel 确实 good. So I'm aware 那 it makes me feel good. In order to illustrate how reinforcement 确实 works, let me give 你 the counter example, which 会 be an aversive agent.

So 我们 have reinforcing agents 和 我们 have aversive agents. Let's say 那 there were compounds in nature 那 exist in plants 那 are aversive. 和 indeed, they are. 和 let's say 那 这些 compounds were present at such low concentrations 那 你 couldn't taste them. Let's say 你 wake up in the 早晨 和 你 go to 你的 refrigerator 和 你 open it up 和 你 are thirsty, 和 so 你 reach 对于 a nice rich red-containing beverage in a glass jar.

Maybe it looks like cranberry juice 或 something of 那 sort. 或 even a nice clear glass of 水. It looks like a jug of 水 或 a glass of 水, 和 你 drink 那. Taste fine to 你. Maybe even tastes great to 你.

和 then let's say 关于 30 分钟 later, 你 feel a little queasy, 你 feel a little off, 你 feel like going back to sleep, 你 just don't feel 非常 good. 你 don't know why, 但 你的 神经系统 is a predictive machine, 和 it has a process in which it back integrates. 或 I 应该 say integrates backwards 进入 你的 immediate experience 那 preceded 那 not so good feeling.

我们 可以 reliably say 那 there is a much lower probability 那 the next 天 when 你 wake up 那 你 会 reach 对于 那 same beverage 或 对于 那 same container even. 和 maybe if 你're in a novel environment, maybe 你're staying in an Airbnb 或 a hotel 或 something of 那 sort, 你 可能 even find 那 你 don't 确实 like the kitchen in which 你 consume 那 beverage in the 首先 place. 和 你 don't know why.

和 unless 你 got 非常, 非常 sick the 天 之前, it's unlikely 那 你 会 have such a strong response 那 你 会 entirely avoid, 对于 instance, 水 或 glass jars containing liquids, et cetera. Let's say 你 went back to the refrigerator 和 你 consume a beverage again 和 你 just didn't feel so well, 你 felt 更少 good than 你 normally 会. Well, even 没有 any ability to taste what's in 那 beverage 和 even 没有 any understanding of what was happening to 你 at a conscious 水平, there is a 非常, 非常 high probability 那 你 会 avoid drinking 那 particular beverage 和 certainly at 那 location 和 in the same volume in the subsequent 天.

那's just the way 那 aversive agents work. 和 they work by way of activating neurons in the gut 那 communicate 与 areas in the 大脑 那 give us 这 feeling of queasiness. 和 对于 some of 你 hearing 这, 那 通路 和 那 association 与 times in which 你 felt queasy 和 as if 你 wanted to vomit is so powerful 那 你 可能 even be feeling some of 那 symptomology now.

对于 certain 人们 那's going to be 增加了 salivation which precedes vomiting, 我们 know 那 there's a class of neurons in the 大脑 relate to an area called area postrema 那 actually stimulates vomiting. 和 if I keep talking 关于 这, I'll probably feel like I want to vomit, so I'm going to move on 从 这 in a moment. So when 我们 ingest caffeine-containing beverages 和 foods, it's the exact opposite scenario as to what I just described.

Caffeine, as a reinforcer, makes us feel slightly better 或 a lot better in the immediate 分钟 和 小时 之后 我们 ingest it. So it's acting as a reinforcing agent not just while 你 are under the effects of caffeine 但 对于 the things 那 preceded the ingestion of caffeine, which is why 你 return again 和 again to caffeine-containing beverages, such as coffee 和 tea 或 maybe even foods 那 contain caffeine, even if the taste of 那些 foods is not something 那 你 会 otherwise consider, 尤其是 delicious.

In fact, most 人们 when they take their 首先 sip of coffee 或 tea 或 other caffeine-containing beverage, they find it to be 非常 bitter. 和 那's not 因为 of the taste of caffeine. It's 因为 of the taste of the beverage itself independent of caffeine. 然而, when caffeine is present in there, they come to prefer 那 taste over most all tastes.

In fact, they 会, as I mentioned earlier, 会 invest a lot of financial resources 和 time 和 能量 to make sure 那 they get 那 beverage. What they're trying to make sure is not 那 they get 那 taste 但 那 they get the caffeine. It is 那 positively reinforcing. 和 the taste 因此 takes on new significance, new meaning, 和 我们 come to associate it as positive.

和 in fact, most of us, including myself, love the taste of espresso, love the taste of coffee, love the taste of yerba maté even if the initial taste, the 非常 首先 time 那 我们 consume 那 beverage, was either neutral 或 negative. 和 那 is all 因为 of the reinforcing properties of caffeine. 和 then, of course, there are the 更多 direct actions of caffeine. 那 is, the faster actions of caffeine.

和 just to list 那些 off again 非常 briefly so 那 你 have them in 心智 going forward, caffeine also 增加 the 释放 of 多巴胺 和 acetylcholine, both of which are neuromodulators in the forebrain, which 增加 clarity of thought 和 你的 ability to rule switch, 你的 ability to move 从 一 context to another 和 change 和 understand the rules of engagement, social engagement, physical engagement, mental engagement, 和 so forth. 和 as I mentioned 之前, caffeine also 增加 the number of 多巴胺 受体 in the reward 通路, such 那 any good thing 那 happens to 你. Any positive experience 那 你 have 会 have a 更多 potent effect on 你的 feelings of well-being.

和 last 但 certainly not least, caffeine acts as an adenosine antagonist. It 减少 你的 feelings of lethargy 和 fatigue 和 你的 desire to sleep by parking in the 受体 对于 adenosine 和 not allowing adenosine to have its pro-sleepy, if 你 会, effects on 你的 大脑和身体. I'd like to take a quick break 和 acknowledge 一 of 我们的 sponsors,

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I'd like to just briefly talk 关于 adenosine 和 some of its molecular features. 和 again, if 你 don't have a background in biology, don't worry. I promise to make 这 非常 clear to everyone.

首先 of all, caffeine is what's called a methylxantine. It's a plant alkaloid. 那's why caffeine itself is 非常 bitter.

Again, if I were to give 你 just the tiniest little bit of pure caffeine, 你 会 find it to be extremely aversive. So 这些 plants 那 have snuck small enough amounts of caffeine 进入 them 或 那 have masked the flavor of caffeine 与 other flavors such 那 bees 和 humans want to consume them, while 我们 don't know what plants think, it does seem 非常 diabolical 和 非常 clever in 那 我们 are seeking out 这些 caffeine-containing plants, beverages, 和 foods even though caffeine itself is 这 alkaloid 那 is 非常, 非常 bitter.

Methylxantine-- 那 is caffeine-- binds to adenosine 受体. 和 there are 确实 二 types of adenosine 受体. There are 这些 so-called A1 受体 和 the A2 受体. 和 they are present in 不同的 parts of the 大脑和身体 at 不同的 水平. 我们 don't have to get too far 进入 受体 subtypes.

更多 importantly to understand is 那 adenosine makes us feel tired 因为 of the way 那 it taps 进入 the ATP 通路. The ATP 通路 is central to 能量 production 和 feelings of overall 能量 in 我们的 大脑和身体 in all cells 和 organ 系统. When caffeine binds to adenosine 受体, it prevents adenosine 从 breaking down certain components of the 能量 production 通路. 和 the net consequence of 那 is 增加了 cyclic AMP.

So basically, when 我们 ingest caffeine, 我们 are biasing 我们的 系统 towards the pro-energetic aspects of 这些 cellular 通路. Now it's 确实 重要 to understand 那, in biology, even if 你 block a 受体 或 你 prevent the activity of an enzyme 和-- at least, in 这 case, 你 end up 与 更多 cyclic AMP, 更多 能量. 你're not 确实 getting 更多 能量. 你're actually borrowing 能量 against an overall 系统 那 is frankly nonnegotiable.

What do I mean by 那? Well, let's say 那 你 were to wake up 之后 six 或 eight 小时 of sleep 和 to drink a lot of caffeine 和 keep drinking caffeine throughout the 天 blocking 那些 adenosine 受体. Yes, 你'll offset fatigue. 你'll offset sleepiness 因为 那 adenosine simply 可以't function. 但 at the point where the caffeine becomes dislodged 从 the adenosine 受体, 你 会 have a massive glut, a backlog of adenosine, 和 你 会 feel extra, extra sleepy.

So 确实, there's no way to create 更多 能量 in 你的 系统. 确实, what 你're doing is 你're changing the timing in which the sleepy signals 和 the 更多 energetic signals are arriving. 和 这 is 确实 重要 to understand as the backdrop to the various tools 那 我们're going to get 进入 next, in which 你 可以 use caffeine 对于 增强 心理表现 和 身体表现 和 other aspects of health.

但 it's 非常 重要 to understand 这 concept 那, when 你 wake up in the 早晨 provided 那 你 slept well 和 enough the 夜间 之前, 你的 水平 of adenosine 会 be 关于 as low as they 会 ever be. Actually, in order to get 你的 adenosine 水平 确实 bottomed out, 你 want to avoid caffeine in the 首先 90 to 120 分钟 之后 waking. 我们'll talk 关于 why 那 is 因为 it turns out there's a way to completely clear adenosine out of 你的 系统 in the 小时 或 so 之后 waking.

但 对于 most 人们, adenosine 水平 are going to be close to their lowest 之后 a good 夜间's sleep. 但 there's 确实 no negotiating the accumulation of adenosine 那's going to occur 和 going to bias 你 towards feeling 更多 sleepy than 你 会. Otherwise, 那's going to occur throughout the 天. There's 确实 no way to eliminate adenosine. All 你 可以 确实 do is block its function.

So it's sort of like borrowing 能量 against the fatigue 那 你 会 inevitably feel. Now 这 actually has a 非常 重要 socioeconomical relevance. 之前 caffeine was regularly consumed by human beings, 我们 were 确实 slaves to the light/dark cycle. 和 这 was 尤其是 true 之前 the presence of artificial lighting. 但 even 之前 the advent of artificial lighting, humans were largely constrained to the outside light/dark cycle.

我们 need to be active 期间 the 天 和 working 期间 the 天, 和 我们 need to be asleep at 夜间. Caffeine allows us to divorce ourselves 从 那 circadian cycle. Circadian just means 关于 24 小时. Caffeine allows us to do 那 at least somewhat by way of increasing 我们的 alertness. 那 is, spiking 我们的 alertness at various times throughout the 天 和 even at 夜间.

这 is how 我们 可以 have shift workers, 对于 instance, 那 可以 sleep 期间 the 天 和 then drink a strong cup of coffee at 8:00 PM 和 then work 进入 the 夜间. 那 ability completely transformed 我们的 society. Now, of course, the healthiest schedule-- 和 我们 know 这 与 certainty. The healthiest schedule 对于 大脑和身体 is going to be alert 期间 the daytime 和 asleep at 夜间. There's no question 关于 那.

Shift workers run 进入 all sorts of health problems. 和 thank 你 shift workers 对于 doing the 重要 work 那 你 do. 我们 need 你. 空气 traffic controllers, paramedics, firefighters, police officers, et cetera. 但 我们 know 那 there are serious health consequences, negative health consequences, 那 is, 对于 shift workers.

但 对于 most 人们 out there, 关于 95% of 人们 follow a typical schedule. They're awake 期间 the 天 和 asleep at 夜间. 和 yet it used to be 之前 the advent of caffeine-containing beverages 那, if 你 were sleepy in the 下午, 你 either had to take a nap 或 battle 那 sleepiness, 那 你的 activity rhythms 和 你的 sleep rhythms were governed by 这些 circadian changes in availability of sunlight 和 when 你 slept.

和 你 just didn't have the ability to ingest a beverage 那 会 增加 你的 水平 of alertness 因为 你 block adenosine. So 这 is 重要 to understand 那, nowadays, 我们 certainly live in a time in which 我们 use-- in fact, 90% 或 更多 of adults 和 half 或 更多 of adolescents 和 teenagers use caffeine as a way to negotiate 与, to borrow against 这 natural pattern of adenosine making us sleepy. 但 again, 你're just offsetting the effects of sleepiness 那 adenosine causes.

你 可以't eliminate the adenosine entirely. The 重要 point is 那 adenosine as a pro-sleep molecule is a nonnegotiable aspect of 你的 biology. In fact, it's so nonnegotiable 那, every 24 小时, 你 are going to 释放 adenosine, 和 你're going to 释放 adenosine in direct proportion to how long 你've been awake.

So the longer 你've been awake, the 更多 adenosine circulating in 你的 系统. There are 确实 only a handful of ways to completely clear out adenosine. The major 一 being to get sleep. The other is to take a short nap, which, of course, is sleep, 但 it's shallow sleep. 或 non-sleep deep rest, so-called NSDR, has been shown to 减少 水平 of adenosine.

和 there are certain things such as viewing 早晨 sunlight, which 因为 of its effects on cortisol, 可以 quote unquote, "clear out adenosine." 我们'll talk 关于 这 in 更多 detail in a few 分钟. 和 there's also 证据 那 certain forms of 运动, provided 那 it's brief 和 intense, 可以 also 减少 adenosine, not just block its effects.

Now 那 我们've talked 关于 some of the incredible mechanisms by which caffeine changes 我们的 experience of life, 增加 alertness 和 情绪, et cetera, I want to talk 关于 the use of caffeine as a tool. Now caffeine is a 非常 potent 和 useful tool 对于 增强 心理健康, 身体健康, 和 表现. 但 there are certain considerations 一 has to keep in 心智, in particular, dose. Now, 首先 off, not everybody 会 respond to the same dose of caffeine the same way, 但 我们 可以 reliably say 那 你的 身体 weight is a good measure by which 你 可以 estimate what a healthy, useful dose of caffeine 会 be.

So 对于 most 人们, ingesting 1 to 3 milligrams of caffeine per kilogram of 身体 weight is going to be the range in which caffeine 可以 have positive effects 没有 making us feel overly anxious 和 give us 那 feeling 那 我们're jumping out of 我们的 皮肤 和 turn the otherwise positive experience of caffeine 进入 an aversive 一. 对于 那些 of 你 那 aren't familiar 与 thinking in terms of kilograms 和 normally think in pounds, I'll just quickly give 你 some general estimations 那, 对于 instance, 100 kilograms equals 220 pounds.

So 对于 me, I weigh 100 kilograms. 那 means 那 1 to 3 milligrams-- again, milligrams, thousandth of a gram. 1 to 3 milligrams of caffeine per kilogram of 身体 weight 会 mean 对于 me. I could safely ingest 100 to 300 milligrams of caffeine in a single dose, in a single drink, if 那's the way I'm consuming it, 或 pill form if 那's the way 那 I'm consuming it.

和 it's 非常 可能 那 那 会 be a tolerable dose. 然而, if 你 are not somebody 那's accustomed to drinking caffeine on a regular basis, I suggest 你 start on the lower end of 那 1 to 3 milligrams per kilogram of 身体 weight range. So 对于 instance, if 你're somebody who weighs 50 kilograms, 那's approximately 110 pounds.

和 你 会 be pretty comfortable ingesting somewhere between 50 和 150 milligrams of caffeine. So what I recommend is 那 人们 who are considering using caffeine as a tool 或 who are already ingesting caffeine, start to think 关于 the dosage of caffeine 那 你 are ingesting 或 plan to ingest 和 the timing in which 你 ingest 那 caffeine relative to certain tasks throughout 你的 天, 你的 waking, 和 你的 sleep. 和 我们'll talk 关于 那 in just a moment.

但 the 首先 step 对于 你 is to figure out how much 你 weigh in kilograms 和 then to go to 那 number of 1 to 3 milligrams of caffeine per kilogram of 身体 weight. 和 那's a good range in which 你 可能 want to explore the use of caffeine in a single application, meaning a single dose. Now, I do realize 那 some 人们 out there are drinking coffee all 天 long 或 having coffee in the 早晨 和 again in the 下午.

What I'm referring to here is the ingestion of caffeine in a single bout, right? 1 cup of coffee 或 2 cups of coffee, 对于 instance, to achieve 那 100 to 300 milligram range if 那's what's appropriate 对于 你的 身体 weight. 但 to avoid any confusion, when I talk 关于 dosage of caffeine, what I'm 确实 talking 关于 is not the total amount of caffeine ingested per 天. I'm talking 关于 the total amount of caffeine ingested in 一 sitting 或 setting, 那 is.

和 if 你're somebody who's drinking caffeine multiple times throughout the 天, 你 可以 imagine-- 对于 instance, let's say the appropriate dose 对于 你 in order to get an enhancement in 心理表现 或 身体表现 is 200 milligrams. 和 你 are somebody who's doing some work in the 早晨, 和 你 want to have 那 lift in the 早晨 to be able to 专注 better. 和 你're doing some physical 运动 in the 下午 或 vice versa 那 你 会 ingest 200 milligrams of caffeine at 二 separate times per 天 separated by 关于 four 小时.

Now 你 don't have to separate them. 你 could put them 二 小时 apart, 对于 instance. 但 我们'll talk 关于 half-life of caffeine 和 so forth. Just keep in 心智 那, if 你're ingesting 200 milligrams of caffeine 和 那's the appropriate dose 对于 你 based on 你的 身体 weight 和 then 你 are ingesting another 200 milligrams of caffeine an 小时 later, 你 are effectively ingesting approximately 400 milligrams of caffeine, which is going to start exceeding the dose in which 你 可以 normally tolerate 没有 feeling anxious 和 jittery.

与 all of 那 said, there is a range of tolerance 对于 caffeine 那's based on 二 things. 一 is a preexisting disposition 那 is whether 或 not 你的 genetics 和 神经系统 和 the backdrop of 你的 life, how much 压力 你're experiencing tends to make 你 feel 更多 anxious 和 alert 和 jittery 之前 你 ingest any caffeine. 和 the other is how so-called caffeine-adapted 你 are.

我们 经常 hear 关于 tolerance. Tolerance means something 非常 具体的. It's the ability to ingest 更多 和 更多 of something 与 a plateau 那 is a no 增加 或 an actual reduction in the effectiveness of 那 thing. 但 here 我们're not 确实 talking 关于 tolerance to caffeine. What 我们're talking 关于 is being caffeine-adapted.

A simple way to understand whether 或 not 你的 caffeine-adapted 或 not is 那, if 你 drink caffeine 和 it tends to 增加 你的 心率 和 make 你 feel 更多 alert 和 a bit 更多 anxious, then chances are 你 are not caffeine-adapted, provided the amount of caffeine is within the healthy range 对于 你, 那 is, the ranges 我们 talked 关于 a moment ago. 然而, here's somebody who drinks caffeine 和 你 actually feel alert 和 relaxed, chances are 你 are caffeine-adapted. 和 so at various times 期间 today's episode, I'll talk 关于 人们 who are caffeine-adapted 和 人们 who are not caffeine-adapted.

我们'll talk 关于 the use of caffeine every other 天. I know a few habitual caffeine drinkers including myself, just the simple mention of 那 probably sounds aversive. 但 there is actually great utility to using caffeine every other 天 as opposed to every 天. 但 just keep in 心智 那 some 人们 会 drink caffeine 和 not get much of a lift 从 it at all. Other 人们 会 drink caffeine, 和 they 会 feel extremely anxious even at dosages far lower than 那 1 to 3 milligrams per kilogram of 身体 weight range 那 I described a moment ago.

So 你 have to take 进入 account individual differences. 那 said, 1 to 3 milligrams of caffeine per kilogram of 身体 weight 对于 a given sitting. 对于 你的 早晨 coffee 或 你的 早晨 yerba maté tea is a good range 从 which to start. 和 I do encourage 你 to go online 和 look up the various beverages 和 foods 那 你 可能 be eating 那 contain caffeine.

对于 instance, some 人们 are surprised to discover 那 the coffee 那 they get 从 some of the 更多 standard popular vendors out there, the small coffee 或 the medium coffee, 对于 instance, 可以 contain as much as 400 to 600 milligrams of caffeine. 和 the large coffee 那 is 经常 sold at 那些 commercial vendors 可以 contain as much as 1 gram, 1,000 milligrams, of caffeine. Now 你 may be adapted to 那 such 那 it doesn't make 你 feel anxious, 但 if 你 wonder why 你 feel irritable 和 你 get a headache when 你 don't get 那 caffeine 或 那 amount of caffeine at precisely the time 那 你're used to getting it each 天, 那's 因为 你 are consuming quite large quantities of caffeine on a regular basis.

So I do recommend whether 或 not 你 drink soda 或 coffee 或 tea 那 你 figure out the source of 那. OK, so figure out what vendor 你 purchase it 从, what kind of coffee, 和 go online 和 spend a little bit of time 因为 the information is out there to discover what 水平 of caffeine 你're actually ingesting. Now if 你 happen to be ingesting 更多 than 1 to 3 milligrams per kilogram of 身体 weight of caffeine, 那's not necessarily bad. 然而, 你 do want to be careful 关于 ingesting 非常 high 水平 of caffeine over long periods of time in 你的 life 因为 there 可以 be issues 那 start to arise.

In particular, a bias towards higher 水平 of anxiety 和 depletion of certain electrolytes. 因为 caffeine is a diuretic 可以 cause 你 to lose sodium 和 other things of 那 sort. 和 also just 从 simply a dependent standpoint, it does appear 那 if 你 ingest high 水平 of caffeine 那 is exceeding the dosages 那 normally 你 could get away 与 和 get just as much mental-增强 和 physical-增强 benefits 那 你 可以 cause some disruption to the microvasculature.

你 可以 bias yourself towards headaches, anxiety attacks, 和 你 可以 become actually quite irritable when 你're not getting 那些 higher 水平 of caffeine. So I do encourage 你 to figure out not just what an appropriate caffeine dosage 会 be 对于 你 但 also how much caffeine 你 可能 already be ingesting.

The 首先 tool I'd like to talk 关于 is 一 那 I've mentioned 之前 on 这 podcast several times. 和 it's something 那 if 你 haven't heard of 会 be 非常 useful to 你. 和 if 你 have heard 这 tool 之前, I'm going to add some additional features to the description of 这 tool 那 应该 make 这 worthwhile 对于 你 as well. 和 那 is to delay 你的 caffeine intake to 90 to 120 分钟 之后 waking up on most 天.

和 I'll be 非常 clear as to 天 in which 你 可能 want to ingest caffeine 更多 closely to when 你 wake up. Why 会 你 want to delay 你的 caffeine intake to 90 to 120 分钟 之后 waking? The answer to 那 is 非常 simple. Many 人们 wake up in the 早晨. They drink caffeine within 10, 20, 30, sometimes within 2 分钟 of waking.

和 they feel 更多 alert naturally. 那 makes sense 因为 of the effects of caffeine in blocking the effects of adenosine 那 I talked 关于 earlier 和 its effects on other 神经递质 系统. 但 then what they find is 那, in the early 下午, in particular, 之后 lunch, they experience a dramatic dip in their overall 水平 of 能量, the so-called 下午 crash.

和 in most cases, the way they respond to 那 is to ingest 更多 caffeine, which indeed 可以 增加 their 水平 of 情绪 和 alertness. 然而, as 我们'll soon talk 关于, there is a problem 与 ingesting caffeine in the 下午 if it falls within 8 或 10 或 dare I even say 12 小时 of going to sleep. 和 那 is, the caffeine ingested in the 下午-- 对于 most everybody, let's say 对于 95-plus percent of 人们-- disrupts the architecture 和 quality of their nighttime sleep.

和 I 应该 say 那 it doesn't necessarily impact their ability to fall asleep 和 maybe even sleep 通过 the 夜间 但 那 the depth 和 quality of 那 sleep is disrupted by consuming caffeine in the 下午. A little bit later, I'll talk 关于 how 你 可以 offset some of 那些 negative effects if 你 absolutely require caffeine in the 下午. 但 there's a huge advantage to restricting 你的 caffeine intake to the early part of 你的 天 但 not consuming caffeine within the 首先 90 to 120 分钟 之后 waking.

In fact, many 人们 find 那 if they delay their caffeine intake to 90 to 120 分钟 之后 waking up 那 they feel 更多 alert in the 早晨, 和 they completely avoid 那 下午 crash. Now 那 said, many 人们, including myself, do need a short nap 或 non-sleep deep rest 或 other form of relaxation 对于 10 to 30 分钟 in the 下午. 那 is natural 和 healthy.

I'm not referring to the need 对于 那 when I refer to the so-called 下午 crash. What I'm talking 关于 in the 下午 crash is a inability to recover 能量 和 专注 和 a need to consume 更多 caffeine just to make it 通过 the 下午. By delaying caffeine intake to 90 to 120 分钟 之后 waking, there are a couple of things 那 are accomplished.

首先 of all, 你 offset 那 下午 crash. 和 这 is an effect 那 many 人们 experience the 非常 首先 time they start delaying their caffeine intake to 90 to 120 分钟 之后 waking. 和 the reason 这 works so well is the following.

As I mentioned earlier, adenosine is a molecule 那 builds up the longer 那 我们 are awake. It is a molecule 那 is reduced 或 cleared 从 我们的 系统 by sleep. So when 我们 emerge 从 sleep regardless of how long 我们've slept, 我们的 adenosine 水平 are lower than they were when 我们 went to sleep the previous 夜间.

If 你 slept well enough 和 long enough, 那些 adenosine 水平 可以 be 非常, 非常 low, 但 they are 从不 completely zero. When 你 wake up in the 早晨, even if 你're 一 of 这些 人们 那 springs out of bed 和 is ready to attack the 天-- 和 here I'm certainly not describing myself. I'm not 一 of 那些 人们. I tend to wake fairly slowly. 但 if 你're 一 of 那些 spring up 和 attack the 天 或 你're 一 of the 人们 who moves 更多 slowly 进入 你的 天, regardless, there's still some residual adenosine in 你的 系统.

和 这 is particularly the case if 你 did not get enough sleep 或 enough depth of sleep the 夜间 之前. The correct ratio is a slow-wave sleep 和 rapid eye movement sleep. 和 对于 那些 of 你 interested in optimizing sleep, I'll just refer 你 to 我们的 master 你的 sleep episode of the Huberman Lab 播客, the perfect 你的 sleep episode of the Huberman Lab 播客. 和 我们 have a tool kit 对于 sleep all of which are available, zero cost, time-stamped, et cetera at hubermanlab.com.

你 wake up in the 早晨. 和 你的 adenosine 水平 are low, 但 they're not zero. 和 if 你 didn't sleep 那 well 或 deeply enough the 夜间 之前, 你're going to have 更多 adenosine in 你的 系统.

你 可能 think the logical thing to do is 因此 to drink caffeine 和 to block the adenosine 那's there. 但 what happens if 你 do 那 is there's an accumulation, a sort of glut of adenosine 那 hangs 大约. 和 then in the 下午, when the effects of 那 caffeine start to wear off, 你 会 experience the so-called 下午 crash.

As I mentioned earlier, there is a way to clear out the adenosine 那's present when 你 wake up in the 早晨 和 to clear it out 本质上 completely 没有 just blocking its 受体 和 letting it accumulate 或 hang 大约. 和 the way to do 那 is to deliberately spike 你的 cortisol. Now, many of 你 have heard of cortisol, the so-called 压力 激素, as a bad thing.

和 indeed, chronically elevated cortisol is a bad thing. It depletes 你的 免疫系统. It's bad 对于 psychosocial effects. It tends to make us feel anxious 和 on 和 on. 但 cortisol itself is not bad.

Cortisol is wonderful. Cortisol 增强 the efficiency of the 免疫系统. It makes us alert 和 focused. It stimulates 我们的 代谢. It does a huge number of positive things, provided 那 it is 释放了 in a circadian fashion.

那 is, at the appropriate times every 24 小时 和 那 it tends to peak 非常 close to waking. In fact, 一 of the reasons 你 wake up in the 早晨, assuming 那 你 weren't woken up by some noise 或 sleeping in an environment 那's too warm, et cetera, is 那 你的 cortisol 水平 start to rise. 和 shortly 之后 waking, 你的 cortisol 水平 会 start to reach their peak.

和 when I refer to a cortisol pulse, 那's just biology nerd speak 对于 a rise 和 peak in cortisol. 你 want 那 cortisol pulse to occur early in the 天 close to waking, 和 你 want 那 对于 a couple of reasons. 首先 of all, if 你 don't restrict 那 cortisol pulse to early in the 天, it 会 tend to bleed 进入 the later parts of the 天. 和 actually, a late shifted cortisol peak is 一 of the hallmark signatures of depression, low-水平 depression, 和 serious depression.

和 it 可以 start to disrupt sleep 和 certainly 可以 disrupt 情绪 代谢 和 你的 免疫系统. So 你 want 那 cortisol peak early in the 天. How do 你 ensure 那 那 happens? Well, 你 wake up in the 早晨. 和 whether 或 not 你're a bounce-out-of-bed type 或 你're 更多 groggy, 你 kind of wade slowly 进入 the 天 type like I am, 你 wake up, 和 你 don't ingest caffeine.

Fine 和, in fact, beneficial to hydrate 与 水 和 electrolytes. Terrific. In fact, I 会 say necessary to get bright light in 你的 eyes ideally 从 sunlight. I've talked 关于 这 many, many times 之前 on the podcast.

If 你 wake up 之前 the sun comes out, then turn on bright artificial lights. 但 then certainly once the sun is out 和 even on cloudy 天, in fact, 尤其是 on cloudy 天, get outside 对于 anywhere 从 5 to 20, maybe even 30 分钟. Do some work outside, take 你的 breakfast outside if 你're a breakfast eater. Get something done outside even if it's just to get outside 和 get bright light in 你的 eyes.

Why? Well, 因为 it's been shown in 研究 on humans 那 getting bright light in 你的 eyes in the 首先 小时 之后 waking 或 as soon as 可能 之后 waking 增加 the peak of 那 cortisol pulse by 50%, 5-0. 和 那 cortisol pulse, yes, 增加 情绪, yes, 增加 alertness, 但 it does 一 other 非常 重要 thing, which is 那, 通过 an indirect 通路, it 可以 clear out any residual adenosine 那 可能 be present in 你的 系统 when 你 wake up in the 早晨.

Again, 这 is going to be 尤其是 重要 对于 那些 of 你 那 are not getting as much sleep 或 as much quality sleep as 你 会 like. It's going to be 非常 重要 对于 你 to get 那 早晨 bright light ideally 从 sunlight, get 那 cortisol peak going. Other ways to 增加 那 cortisol peak 会 be to do some physical activity.

If 你 don't have time to do a full workout, well then, getting some movement-- 10 分钟 of skipping rope 或 even 5 分钟 of skipping rope 或 jumping jacks 或 walking if 那's all 你 have time 对于 ideally while getting the sunlight in 你的 eyes. 但 那's going to zero out the adenosine present in 你的 系统. If, 然而, 你 were to wake up 和 immediately drink caffeine-- caffeine itself 可以 stimulate the 释放 of cortisol a little bit 更多 than it 会 otherwise be present in 你的 系统. 但 by blocking 那些 adenosine 受体 和 因为 of the indirect effects of caffeine on the cortisol 系统, 你 actually are 减少 the clearance of adenosine 那 会 otherwise occur.

So I realize 那's a mouthful. Just to be 非常 clear, if 你 wake up 和 你 ingest caffeine right away, 你're blocking the adenosine 受体, 但 你're not clearing it out. 你're also preventing cortisol 从 having its normal 增加 和 rise such 那 it 可以 directly clear out adenosine 因为 cortisol 可以 clear out adenosine.

和 那's what 你 want. 你 want to be at maximum alertness 和 专注 in 你的 早晨 和 throughout 你的 天. 和 by delaying 你的 caffeine to 90 to 120 分钟 之后 waking, 你 set up 你的 系统 so 那 你 get 那 早晨 cortisol peak. Ideally, a peak 那's even greater 因为 你're getting 你的 bright light viewing.

和 then when 你 ingest 你的 caffeine 90 to 120 分钟 之后 waking, not only 会 你 be craving it just a little bit, 但 你 会 be drinking 那 caffeine on an already existing backdrop of 增加了 alertness 对于 二 reasons. 一 is adenosine is zeroed out, 和 你的 cortisol peak is higher. 和 so now when 你 ingest caffeine, 你 可以 actually ingest 水平 of caffeine 那 are a little 更多 reasonable 那 almost 与 certainty are going to fall in 这 1 to 3 milligrams per kilogram dosage 和 会 allow 你 to feel 确实 alert 和 会 carry 那 alertness well 进入 the 下午 小时 没有 the need to drink 更多 caffeine 和 thereby 会 prevent 你 从 drinking caffeine 和 disrupting 你的 nighttime sleep.

和, of course, by getting better nighttime sleep, 你're going to zero out 你的 adenosine even 更多. So what I'm describing here are 本质上 二 tools. I'm telling 你 to get 早晨 sunlight 和 maybe some 运动 in conjunction 与 那 even if it's brief 运动. 但 the main tool of delaying caffeine 90 to 120 分钟 之后 waking has immediate effects, 但 it also sets in motion a cascade 或 domino falls 那 lead to better sleep 和 更多 wakefulness the next 夜间 和 the next 天 和 so on 和 so forth.

Now I realize there are some 人们 who just simply cannot 或 会 not delay their caffeine 90 to 120 分钟 之后 waking 对于 whatever reason.

首先 off, let me say 那, if 你 are somebody who likes to wake up 和 do 非常 intense 运动 within the 首先 90 分钟 之后 waking, well, in 那 case, it 会 be appropriate to ingest 你的 caffeine just prior to doing 那 运动. Not a problem. Not a problem. 但 你 应该 expect 那 the combination of drinking caffeine 非常 shortly 之后 waking plus exercising 非常 intensely shortly 之后 waking 会 增加 the intensity of 那 early 下午 和 下午 fatigue 那 你 feel.

Now 对于 some 人们, 那's a great thing. They 可以 afford to take a nap 或 do non-sleep deep rest, step away 从 work, 和 so forth. In 那 case, I strongly encourage 你 to do whatever it is 那 allows 你 to get regular 运动 因为 regular 运动 is going to be 非常 beneficial. In fact, 我们 did an entire episode called tool kit 对于 fitness 那 describes a couple of 不同的 但 确实 一 main structure 那 allows 你 to get the appropriate amount of resistance 训练 和 cardiovascular 训练 和 flexibility 训练 throughout the 周.

I happen to follow 那 program, 和 it works 非常 well. 和 it does involve some of 那些 workouts to come 非常 early in the 早晨 shortly 之后 waking. 和 in 那些 cases, I do ingest caffeine just prior to 那些, so within 10, 20 分钟 of waking. 然而, on other 天, I personally delay my caffeine intake 90 to 120 分钟, 和 I've done 那 to great benefit.

和 most 人们, if not, all 人们 那 try 那, have reported the same. I 应该 mention 那 some 人们 会 find getting out to 那 90 分钟 to be excruciatingly difficult 因为 they're so accustomed to ingesting caffeine close to waking up. In 那 case, maybe just push out 你的 caffeine intake by 关于 15 分钟 each 天 until 你 hit 那 90 to 120-分钟 mark. 和 那 会 make it much easier. It 可能 take 你 a 周 或 so to get there.

但 once 你 get there, 你'll find it to be quite easy to maintain. The other thing is 那, if 你 are somebody who insists on drinking caffeine 非常 shortly 之后 waking, I 会 encourage 你 to drink half of 你的 caffeine then 和 then the other half of 你的 caffeine 关于 an 小时 later. 那 also 会 help offset some of the 下午 crash 对于 reasons related to the so-called kinetics of caffeine.

Caffeine has a quarter life of 关于 12 小时. 那 means 那 if 你 were to ingest a cup of coffee at let's say 8:00 AM-- 和 let's say 100 milligram coffee just 对于 sake of simplicity, 那 关于 25% of 那 caffeine action-- 我们 wouldn't 确实 say 25 milligrams, 但 关于 25% of 那 caffeine action 会 still be present at 8:00 PM 那 夜间, which is pretty remarkable. So there's a long arc of caffeine effects, 和 这 is why it 可以 impede sleep if 我们 take caffeine in the 下午.

但 again, if 你're somebody who wakes up 和 你 确实 need caffeine right away 和 你 refuse to do 这 90 to 120-分钟 delay thing 那 I'm talking 关于, well then, in 那 case, I 会 drink half of 你的 caffeine upon waking 和 then a little bit 更多 或 the other half 关于 an 小时 later. 和 那 会 extend the arc of 那 caffeine effects such 那 你 don't need it again in the 下午 因为 你 won't experience the 下午 crash. 因为 of the way caffeine works, I 应该 mention 那, if 你 ingest caffeine on an empty stomach, it 会 have a 更多 potent stimulant effect.

那 会 also tend to 增加 the 水平 of jitteriness 那 caffeine 可以 produce. Later, I'll talk 关于 ways to offset 那 jitteriness, 但 I'll just tell 你 一 tool now. Many 人们 opt to take 100 milligrams of theanine, T-H-E-A-N-I-N-E, theanine, as a way to offset some of 那 jitteriness.

Theanine 会 减少 the jitteriness of caffeine, which is why many 能量 drink manufacturers 和 even some coffee manufacturers are now putting theanine in 能量 drinks 和 in ground coffee 因为, no surprise, it allows 人们 to consume 更多 of 那 beverage 和 thereby purchase 更多 of 那 beverage, which is what 这些 vendors want 没有 feeling overly anxious 和 jittery. So 你 可以 take pill form theanine if 你 want 与 你的 caffeine. I don't tend to do 那. Rather, I control the total dosage of my caffeine.

I do tend to consume caffeine on an empty stomach 因为 I do restrict my caffeine intake to the early part of the 天. 和 I generally eat my 首先 meal somewhere 大约 11:00 AM, 和 then I generally my last meal some time 大约 8:00 PM 或 so. 那些 are averages. I 会 say plus 或 minus an 小时. 和 那's not 因为 I'm religiously following any kind of time-restricted feeding. It's just 那 tends to work best 与 my schedule 和 my appetite.

但 again, 那's a general theme. There are 天 in which I wake up 和 I'm 非常 hungry, 和 I 可能 ingest something, small snack 或 something. 或 if I'm meeting somebody 对于 breakfast, sometimes I'll have breakfast. Sometimes I won't. 和 so on 和 so forth.

The point is 那 你 可以 get away 与 drinking 更少 caffeine to get the stimulant effect if 你 do it on an empty stomach. 和 if 你're somebody who likes to 运动 on an empty stomach-- 和 I'm 一 of 那些 人们-- well then, ingesting caffeine just prior to 运动 可以 be a fantastic tool. A little bit later, 我们'll talk 关于 some of the 身体表现-增强 effects of caffeine. 但 I'll just briefly jump to a point 关于 那 as 我们 relate to 早晨 运动.

If 你 are somebody who regularly ingests caffeine-- 和 我们 可以 define regularly by, if 你've ingested caffeine every 天 对于 the last 二 周, 你're a regular consumer of caffeine. Whereas if 你're somebody who only ingests caffeine somewhere between 二 和 four times per 周, well then, 你 are not a regular consumer of caffeine. 你're an intermittent user of caffeine.

Well, if 你're somebody who's a regular user of caffeine, the 表现-增强 effects of caffeine are going to be most dramatic if 你 take 二 或 三 天 off 从 drinking caffeine, which to my 心智 as a-- I don't want to call myself a caffeine addict 但 a regular caffeine user. 那's a horrible notion to me, it is an aversive notion, 因为 I do like the effects of caffeine so much. 但 if 你 确实 want to see the maximum 表现-增强 effects of caffeine, 你 会 do either 一 of 二 things. 你 会 either abstain 从 caffeine 对于 a few 天 或 三 天 prior to ingesting caffeine, 或 你 会 use caffeine on an empty stomach.

It's 非常 clear 那 caffeine on an empty stomach 增强 both the mental 和 physical 增强 effects of caffeine. 和, of course, all of 那 has to be stated on the backdrop of consideration 那 你're 非常, 非常 hungry, it 可以 be make it hard to concentrate 和 so on 和 so forth. So I'm not encouraging 人们 to starve themselves by any means. Certainly, don't do 那.

但 if 你 want to maximize the 表现-增强 effects of caffeine, 你 会 consume it on an empty stomach. 和 then as a final point to 那, caffeine is a diuretic. It causes us to lose fluid 和, along 与 那 fluid, to excrete sodium 因为 of the effects of caffeine on various processes within the kidney. So 一 thing 那 works 非常 well to maintain 情绪 和 alertness longer given a certain amount of caffeine intake 和 to avoid the jitteriness 和 what 可以 sometimes feel like a crash 或 low 血液 sugar feeling 或 even blurry vision is to make sure 那 你 consume at least an equal volume of 水 与 你的 caffeine.

和 ideally, 那 水 会 contain maybe a small pinch of salt 或 some sort of electrolyte drink-- 或 powder, rather. 对于 me, I use element. Full disclosure, they are a podcast affiliate 和 sponsor. 但 你 don't need to do 那. 你 could simply just have a glass of 水 alongside 你的 coffee 或 espresso 或 你的 yerba maté 和 just put a small pinch of sea salt in 那 或 evem just playing table salt.

和 那 会 help offset some of the jitteriness of caffeine. A lot of 人们 think 那, when they ingest caffeine, they get the jitteriness 和 crash 因为 their 血液 sugar is low. 和 while 那 可以 be the case, oftentimes, it's simply 因为 of the excretion of sodium 那's occurred when they've ingested caffeine. So I encourage 你 to hydrate well 和 to hydrate 与 something 那 contains a little bit of sodium.

Obviously, not so much 那 增加 hypertension 或 something of 那 sort 但 a small amount of sodium 或 an electrolyte drink like Element. 和 there are other electrolyte drinks out there 那 可以 accomplish the same, of course. Just a couple of quick notes 关于 theanine 因为 there are a growing number of products out there 那 contain theanine. 和 there's certainly a growing number of 人们 out there who are using theanine 对于 the effect 那 I described 之前, which is to offset some of the jitteriness associated 与 caffeine-containing beverages 或 foods.

和, of course, I 应该 mention 那 I've talked 关于 the effects of theanine on sleep at 那 sleep tool kit 那 你 可以 find as a free download. 你 don't even have to sign up 对于. Anything 你 just download it 从 hubermanlab.com.

Go to the menu, go to a newsletter. 你'll see the tool kit 对于 sleep. 你'll see 那 the so-called sleep stack 那 I use 和 recommend includes magnesium 3 和 8, something called apigenin 和 theanine, 尽管 那 sleep stack is designed to be taken 30 to 60 分钟 prior to sleep. 和 I make the point there, 和 I'll make it again here 那 ingesting theanine prior to sleep is not a good idea if 你 are somebody who tends to have 非常 vivid dreams, 夜间 terrors, 或 夜间 walk-- sleepwalking, excuse me, et cetera.

In 那 case, eliminate theanine 从 the sleep stack.. . 然而, a number of 人们 are using theanine, 和 products are using theanine to offset jitteriness 从 caffeine-containing products 期间 the daytime, daytime consumption, 那 is. A couple of notes 关于 theanine-- theanine is something 那 is present in green tea, right? It's now been created as a supplement. It's what's called a nonprotein amino acid.

So while there are amino acids 和 proteins, there are, of course, amino acids 和 nonproteins. 和 theanine is 一 such nonprotein amino acid. Theanine tends to stimulate the so-called glutamate 和 glutamine 通路. It's actually 非常 相似的 to glutamate 和 glutamine, 和 it has a lot of effects on a lot of 不同的 aspects of the 神经系统.

但 the general effect of theanine is to compete 对于 the 受体 对于 certain 神经递质. 和 the 神经递质 I'm referring to are all excitatory 神经递质, things like glutamate. 和 they govern a tremendous amount of 我们的 daily thinking 和 action 和 feeling, et cetera, 因为 they're present at so many connections between neurons in the 大脑.

Theanine competes 对于 the 受体 对于 glutamate 和 tends to 减少 我们的 overall 水平 of alertness. So 确实, when 人们 take theanine along 与 caffeine, what they're doing is they're 确实 taking a slight-- I don't want to call it depressant to the point where it misleads 人们 和 makes 人们 think 那 it 会 make 你 depressed. The word is a little bit misleading. 但 it tends to 减少 或 blunt some of the 更多 excitatory pro-alertness actions of neurons in the 大脑.

So when 你 take it alongside caffeine, tends to, quote unquote, "even things out a bit." I 应该 mention 那 the dosages of theanine 那 are effective 对于 offsetting the jitteriness of caffeine is 200 to 400 milligrams, 和 the 研究 那 I was able to find showed 那 本质上 up to 900 milligrams per 天 可以 be safe. 但 那's a 非常 high dosage of theanine. In fact, so much so 那 it 可能 增加 sleepiness to the point where it wouldn't feel good.

There are also some positive effects of daytime consumption of theanine 那 are independent of 减少 the jitteriness of caffeine. 对于 instance, there's a 研究 demonstrating 那 17 天 of ingesting theanine at 这些 200 to 400 milligram dosage at 一 to 三 times per 天 可以 减少 depression 和 anxiety. There are also some good 数据 out there showing 那 theanine 可以 have positive effects on endothelial cells-- so 血管, capillaries, 和 so on-- 和 增加 some of the function of 血管, allowing them to pass 更多 血液 通过 them 和 give them a little bit 更多 elasticity, if 你 会.

So theanine has certain pro-sleep effects if it's taken prior to sleep. It 可以 增强 the quality, depth, 和 duration of sleep. Again, if 你're a sleepwalker 或 somebody who has extremely vivid dreams 从 which 你 wake up in the middle of the 夜间, probably best to leave out theanine 或 maybe 减少 the dosage down to 100 milligrams. 和 if 那's still too much, then eliminate it completely.

但 theanine 可以 be terrific 对于 增强 quality, depth, 和 duration of sleep. It 可以 also 减少 the jitteriness associated 与 caffeine-containing beverages 和 foods. 和 it has certain antidepressant 和 pro-endothelial effects. 那 is, it 可以 offset depression. It 可以 offset anxiety, 尽管 那些 are minor effects, subtle effects.

和 it has been shown to 改善 endothelial cell. 那 is, vessel 和 capillary function 和 structure in ways 那 可以 be beneficial 对于 both 大脑和身体. Now 一 final point 关于 theanine 那's worth paying 注意力 to is 那 the kinetics of theanine are such 那 你 don't need to take theanine every time 你 ingest a caffeinated beverage.

When 我们 ingest caffeine, the peak effects of caffeine occur 关于 30 分钟 之后 我们 drink it. 和 there, I'm assuming 一 takes it all at once. 和 这 is a key point 那 我们'll come back to later rather than sipping 你的 coffee slowly over a couple of 小时 或 an 小时. If 你 drink all 200 或 300 milligrams of caffeine in 你的 coffee 或 600 milligrams of 你的 coffee if 你're getting 一 of 那些 commercial coffees 和 你 take theanine along 与 it, theanine 会 block some of the jitteriness 和 anxiety-inducing effects of caffeine 那 可以 occur 对于 much longer than the effects 那 caffeine lasts.

So the peak in theanine occurs 关于 an 小时 之后 ingestion. I suppose if 你 want to get 确实 fancy 和 确实 dial in the kinetics, 你 could ingest theanine 关于 half 小时 之前 你 ingest 你的 caffeine. 但 I think 那's getting a little bit excessive in terms of controlling 你的 microenvironment, if 你 会. I think it 会 be perfectly fine to take a 100 to 200 milligram capsule of theanine along 与 你的 coffee 或 tea 或 so forth 和 just realize 那 if 你 drink 更多 caffeine 或 你 extend 你的 caffeine intake over several 小时 那 你 don't necessarily have to take theanine repeated times throughout the 天.

I'd like to take a brief break 和 thank 我们的 sponsor, InsideTracker. InsideTracker is a personalized nutrition platform 那 analyzes 数据 从 你的 血液 和 DNA to help 你 better understand 你的 身体 和 help 你 reach 你的 health goals. I've long been a believer in getting regular 血液 work done 对于 the simple reason 那 many of the factors 那 impact 你的 immediate 和 long-term health 可以 only be analyzed 从 a quality 血液 test.

The problem 与 a lot of 血液 和 DNA tests out there, 然而, is 那 你 get 数据 back 关于 metabolic factors, lipids, 和 激素, 和 so forth, 但 你 don't know what to do 与 那些 数据. InsideTracker solves 那 problem 和 makes it 非常 easy 对于 你 to understand what sorts of nutritional, behavioral, maybe even supplementation-based interventions 你 可能 want to take on in order to adjust the numbers of 那些 metabolic factors, 激素, lipids, 和 other things 那 impact 你的 immediate 和 long-term health to bring 那些 numbers 进入 the ranges 那 are appropriate 和 indeed optimal 对于 你.

If 你'd like to try InsideTracker, 你 可以 visit insidetracker.com/huberman 和 get 20% off any of InsideTracker's plans. 那's insidetracker.com/huberman to get 20% off. Let's talk 对于 a moment 关于 when to avoid caffeine. 和 in the same stroke, let's also talk 关于 some of the myths 大约 caffeine.

对于 instance, 一 of the major myths 大约 caffeine is 那 it 可以 增加 osteoporosis. It turns out 那, while there is a relationship, of course, between calcium 和 osteoporosis-- 那 is reductions in bone density. 和 it is the case 那 caffeine 可以 extract calcium 从 certain 组织. The large scale 研究 那 are out there 本质上 prove 那, if 人们 are ingesting enough calcium 通过 their diet, which most everybody is-- 尽管 certainly, there are some 人们 那 need to supplement calcium 或 make it a point to consume 更多 calcium-containing foods.

但 assuming 那 你 are getting adequate 水平 of calcium, there is no direct relationship between caffeine intake 和 osteoporosis, at least not 那 I'm aware of. I know 这 was debated 对于 a number of years in the literature, 但 the literature seems to have arrived at a general consensus now 那 caffeine itself is not going to create 或 exacerbate osteoporosis, provided 人们 are getting enough calcium 通过 their diet. 那 is, 通过 foods, 通过 supplementation, 或 both.

Some of the other myths 大约 caffeine are 那, 对于 instance, caffeine 会 减少 testosterone 水平 或 会 减少 estrogen 水平. Other myths out there are in exact opposite to 那, 那 caffeine 会 增加 testosterone 水平, in particular, free testosterone 水平. There have been some large scale 研究 addressing the 激素 effects of caffeine. They are a little bit difficult to do. I 应该 just mention 那 caveat.

和 the reason they are difficult to do is 因为 90% of adults are consuming caffeine. 和 因此, 你 可以 imagine it's 非常 hard to find a control group to compare the caffeine consumers to. In particular, a control group 那's well controlled 对于 other things like lifestyle, diet, 运动, et cetera. 然而, when 一 controls as well as 一 可以 对于 all the various factors 那 could impact 激素, what 一 discovers is 那 caffeine intake, at least at the dosages 我们 talked 关于 earlier, 1 二 3 milligrams per kilogram of 身体 weight 或 even up to double 那, 那 there are no consistent 增加 或 reductions in testosterone 或 estrogen in men 或 women 那 可以 be directly attributed to the caffeine intake.

和 I say directly attributed 因为 in 这些 association 研究, 一 总是 has to wonder, 对于 instance, if 因为 人们 are ingesting 更多 caffeine, they have 更多 能量 和 因此 exercising 更多. 和 运动 is known to have effects on testosterone, estrogen, 和 other 激素, whether 或 not the effects of caffeine on 那些 激素 is indirect 和 so on 和 so forth. 和 这 all just underscores the challenges of doing 研究 on humans in the wild in their natural habitat of living as opposed to an acute 研究 as it's called to bring someone 进入 the laboratory 和 studying them just 对于 那些 小时 或 moments.

与 all 那 said, there does appear to be a relationship between caffeine intake 和 so-called sex 激素 binding globulin, which is a protein present in the 身体 of both men 和 women 那 binds to the sex steroid 激素-- testosterone 和 estrogen-- 和 prevents them 从 being in their free 或 active form. It has been shown 那 ingestion of caffeine-- even in the sorts of dosage ranges 那 are considered safe 和 那 我们've been discussing-- 可以 增加 sex 激素 binding globulin such 那 it 可以 slightly 减少 overall 水平 of free testosterone 和 free estradiol in women. Now 那些 effects are relatively minor, 但 they do exist.

If any of 你 are interested in reading further 进入 the effects of caffeine on 激素, I'll just refer 你 to a couple of 研究. 我们 会 link to 这 in the show note caption. The title of the 研究 is "Consumption of caffeinated beverages 和 serum concentrations of sex steroid 激素 in US men." 和 within 这 研究, there is a reference to a equally sized empowered 研究 done on women, both of which converged on the same conclusion, by examining 更多 than a thousand.

So in 这 case, 1,410 men 或 更多 than a thousand women, 那 there are 增加 in sex 激素 binding globulin associated 与 增加了 intake of coffee, in particular. 但 they were able to narrow 那 down specifically to ingestion of caffeine. So it's not coffee per se 那's causing the 增加 in sex 激素 binding globulin. It's actually caffeine itself.

So again, the 增加 in sex 激素 binding globulin were not so significant 那, at least to my 心智, they seem like a concern, 尽管 I think 那 it is worth noting 那 if 你're going to consume caffeine 那 你 probably want to consume caffeine in a way 那 is in dosages 和 与 the sort of timing 那 会 allow 你 to get away 与 ingesting caffeine 但 not to excess, so to derive the benefits of caffeine 没有 对于 instance driving up sex 激素 binding globulin too far.

Now why 会 那 be a good idea? Why 会 你 want to make sure 那 你 have enough free testosterone 和 free estrogen? Well, some of 那 is related to the acute effects of 那些 激素 in terms of well-being 和 libido 和 力量 和 情绪, et cetera, 但 some of 那些 also relates to the longer term effects of sex steroid 激素. Many 人们 don't realize 这, 但 the sex steroid 激素 operate on the 受体 at the surface of cells to have immediate effects.

但 they also 可以 enter cells 和 actually go 进入 the nucleus of cells where the DNA of 那些 cells are contained 和 control gene expression in 那些 cells. So the sex steroid 激素, testosterone 和 estrogen, are controlling a lot of 不同的 cellular functions over long periods of time. So blunting their action over long periods of time is probably not a great idea. 但 again, at the dosages of caffeine 那 我们're talking 关于 today, 1 to 3 milligrams per kilogram of 身体 weight, unlikely 那 the 增加 in sex 激素 binding globulin 那 一 experiences 从 那 are going to be detrimental.

和 certainly, the positive effects of caffeine 那 一 experiences in terms of 心理表现 和 身体表现 和 the fact 那 it 增加 能量 to do the sorts of things like 运动 那 我们 know 可以 profoundly 改善 激素 profiles, twofold 或 threefold improvement in 激素 profiles. In 那 case, it seems 那 ingesting caffeine is overall a good thing, provided it's not in excess. 那 also makes 这 the appropriate time to mention 一 of the 更多 impressive effects of caffeine, which is on overall 水平 of 情绪 和 心理健康.

There are several 研究 on 这, 但 the 一 那 I'm particularly fond of was published in 2019 in Psychiatry 研究. 和 the title of the paper is "Inverse association between caffeine intake 和 depressive symptoms in US adults." 和 这些 are 数据 从 the National Health 和 Nutrition Examination Survey. 和 the basic takeaway is 那, while, of course, there are a ton of 不同的 factors 那 are going to relate to whether 或 not 人们 are depressed 或 not, life circumstances, genetics, 和 so on, 那-- 和 here I'm quoting 从 the 研究. "Caffeine's psychostimulant properties-- 那 just means the ability to make us feel 更多 alert 和 positive-- appeared to protect against depressive symptoms."

和, of course, they acknowledge 那 additional 研究 are needed, 但 这 is just 一 of several 研究 pointing to the fact 那 人们 who regularly ingest caffeine in the appropriate dosages do seem to enjoy an antidepressive effect overall. I wouldn't want anyone to consider caffeine a treatment 对于 severe depression 或 at least not alone a treatment 对于 severe depression. 但 provided the anxiety-inducing effects of caffeine 可以 be kept in check 通过 use of theanine 或 making sure 那 the dosage 和 the timing of caffeine ingestion is correct, then caffeine overall seems to be good 对于 我们的 情绪 和 prevent depression 或 at least keep depression at bay when depression 可能 otherwise surface 或 be 更多 severe.

和, of course, there are the don'ts surrounding caffeine intake as it relates to sleep. 和 to put it 非常 simply, sleep-- 那 is getting enough quality sleep each 夜间-- is the foundation. It is the bedrock of 心理健康, 身体健康, 和 表现. Sleep 和 the power of sleep far exceeds any nootropic 你 could ever take, any prescription drug 你 could ever take, any health-promoting tool 对于 你的 免疫系统, 你的 代谢, 你的 mental function, 你的 physical function 你 could ever take. Sleep is the bedrock.

I know a lot of 人们 experience challenge 与 sleep. Nobody is perfect 关于 sleep. 那's 重要 to keep in 心智. I think a good goal is to get enough quality sleep of sufficient duration 80% of the nights of 你的 life 和 then as much as 可能 to make sure 那 the remaining 20% of nights 你 are not getting enough sleep 对于 good reasons as opposed to hard reasons.

Good reasons 会 include raising children. 那's 重要. 之后 all, every species desires to make 更多 of itself 和 to preserve 和 extend the well-being of its young, so child-rearing is a perfectly legitimate reason to get a lack of sleep. 但 你 确实 want to strive to get quality sleep most nights of 你的 life, which means 那, even if 你're somebody who 可以, quote unquote, "drink an espresso" 和 then fall right asleep, 那 你 avoid caffeine intake in the 12 小时 prior to sleep.

I realize not everyone 会 be able to do 那. 和 in fact, I sometimes violate 那, so I tend to go to sleep 大约 10:00 PM every 夜间, sometimes 11:00, occasionally 12:00 midnight, 但 usually 大约 10:00 PM every 夜间. I confess 那 my last ingestion of caffeine is not 总是 10:00 AM 或 prior to 那, so sometimes I 会 have caffeine up until 11:00 AM 或 maybe noon. 和 非常, 非常 rarely, I'll have an 下午 coffee 或 espresso 或 noncalorie-containing soda 或 tea 或 something 那's of 那 sort.

但 I 确实 tried to restrict my caffeine intake to the early part of my 天 那 is 之前 noon, given 那 I go to sleep 大约 10:00 PM each 夜间. 和 I strongly encourage everyone out there to try 和 limit their 下午 caffeine intake. 这 is something 那 Dr. Matt Walker, who's an expert sleep researcher out of University of California Berkeley Psychology 和 neuroscience department there, author of the incredible book Why 我们 sleep. He's been on 这 podcast, many other podcasts, talking 关于 the importance of sleep.

He 会 remind us, 和 I'll remind 你 now 那 the quarter life of caffeine is 12 小时. I mentioned 这 earlier, 但 I'm going to repeat it again. 和 那 means 那, if 你 ingest caffeine at noon, 25% of its effects 更多 或 更少, OK?

I'm using a broad stroke here to talk 关于 quarter life. 25% of 那 is still going to be bioactive at midnight 那 夜间, which 会 disrupt the early phase of 你的 夜间, the amount of slow-wave sleep, which then in turn 会 disrupt the amount of rapid eye movement sleep, which 会 disrupt 你的 emotional processing 期间 the following 天 和 so on 和 so forth. None of 这 is to say 那 if 你 have the occasional cup of coffee in the 下午, 那 it's going to completely demolish 你的 sleep/wake cycle forever. 但 I 确实 encourage 人们 to avoid drinking caffeine in the 12 小时 prior to sleep.

和 if 你 可以't do 那, within the 10 小时 prior to sleep. 和 if 你 可以't do 那, within the 8 小时 prior to sleep. So 确实 try 和 limit 你的 caffeine intake in the 8 to 12 小时 prior to going to sleep at 夜间. 和, of course, slow-wave sleep, aka deep sleep, is the sleep 那's associated 与 somewhat mundane dreams, which makes it sound like it 可能 not be 那 重要.

但 it's also the sleep 那's associated 与 growth 激素 释放, which is 重要 对于 protein synthesis, repair of all bodily 组织 和 代谢. 和 slow-wave sleep is also critically attached to 你的 免疫系统's ability to clear out bacteria 和 viruses 那 可能 otherwise infect 你的 组织.

Now I'd like to talk 关于 caffeine 和 表现. 和 那 includes both 心理表现 和 身体表现. Now I'd like to talk 关于 caffeine 和 its positive effects on 表现 when used correctly. 和 here 我们 are referring to both 心理表现 和 身体表现.

The exploration of caffeine as a pro-表现 tool has been explored since the 1930s, at least 那's some of the earliest documented literature on 这. 尽管 I have to imagine, given 那 人们 have been using caffeine 对于 much longer than 那, 那 long ago somebody realized 那, by ingesting a certain plant, 那 they felt much 更多 alertness 和 were able to hunt 和 gather 或 do any number of 不同的 things better 和, as a consequence, decide to consume 更多 of 那 plant. Now 这些 天, 我们 consume a lot of caffeine in the form of coffee 和 tea mainly, 和 some 人们 consume it in the form of caffeine tablets 或 能量 drinks, et cetera.

Across the board, 一 finds 那 caffeine intake at a 水平 of 1 to 3 milligrams per kilogram of 身体 weight 改善 reaction time. 那 is, it 减少 the amount of time to take a physical action 或 to answer a question correctly 与 a verbal response. It 可以 also 改善 coordination. It 可以 also 改善 memory, 尽管 I do want to mention 那, whereas most 研究 of the effects of caffeine on improving mental 和 身体表现 involve taking caffeine at 1 to 3 milligrams per kilogram of 身体 weight 之前 the mental task 或 physical task, there is also a pro-表现 effect of caffeine on memory if 一 takes caffeine 之后 learning certain material 或 I 应该 say being exposed to certain material.

我们'll come back to 那 in a few 分钟.

If 一 examines reaction time, 情绪, alertness, 专注, 和 memory 或 the ability to call up information 从 memory, 或 physical dexterity, power output, 耐力, 和 overall feelings of well-being 期间 运动 和 exertion, caffeine has been shown in numerous 研究 in both men 和 women to 改善 all of 那些 metrics significantly. So 这 is all just to say 那 caffeine is an incredible 表现-增强 tool. Now, what's not obvious 从 the statement 那 caffeine is a 表现-增强 tool across the board 和 in men 和 women 和 in 不同的 contexts is 那 the way in which caffeine is taken is 非常 重要.

因为 90% 或 更多 of adults consume caffeine, finding controls 对于 研究 of caffeine is 确实 challenging. 那 is, finding 人们 who don't ingest caffeine regularly is a 非常 challenging task 对于 the researcher. 和 as a consequence, many of the 研究 of caffeine on human beings involve depriving regular caffeine users of caffeine 和 then examining the effects of caffeine given 之后 a period of, say, 5 to 15 天 of abstinence in a person 那 is 本质上 experiencing mild withdrawal symptoms 因为 they haven't had the caffeine 那 they were used to getting.

So 这 is an 重要 point. 和 it's a point 那 可能 exacerbates the observed pro-表现 effects of caffeine. Now all of 那 isn't necessarily a problem, provided 你 keep it in 心智. 和 it actually points to a way in which even if 你're a regular caffeine user, 你 可以 extract 更多 of the benefits of caffeine. The simplest way to do 这, 对于 instance, is to look back to what 我们 talked 关于 earlier in terms of the need to have most of 你的 cortisol 增加 restricted to the 小时 或 小时 just 之后 waking in terms of 情绪 和 alertness 和 表现.

一 of the ways to 增加 the peak of 那 cortisol early in the 天 is to consume caffeine shortly 之后 那 peak occurs. 和 这 was 确实 nicely demonstrated in a 研究 entitled caffeine stimulation of cortisol secretion across the waking 小时 in relation to caffeine intake 水平. 我们 会 provide a link to 这 研究. It's a somewhat complicated 研究 因为 they looked at a bunch of 不同的 times of 天 对于 caffeine intake.

和 I 应该 mention, in 这 研究, they use 这 300 milligrams per 天 或 600 milligrams per 天. So 那's quite high, 尽管 对于 人们 of sufficient 身体 weight 和 who are accustomed to taking caffeine, it's certainly not going to be in excess of what a lot of 人们 out there are taking.

但 basically, what they observed was the following. Cortisol responses to caffeine are reduced 但 not eliminated in 人们 who consume caffeine on a daily basis. What 这 means is 那, if 你 wake up-- as I recommended earlier, 你 avoid drinking caffeine 对于 the 首先 90 to 120 分钟 之后 waking, 但 你 do get some sunlight 或 other bright light in 你的 eyes in 那 time, maybe even get some 运动 in 那 time, which 会 be even better-- 和 then 你 ingest caffeine, 你 会 get a further 增加 in cortisol, which, provided it's restricted to the early part of the 天, is a good thing overall 对于 情绪 和 alertness.

So 这 is a simple 表现-增强 tool, which is to stack caffeine on the tail of 那 early cortisol peak. I 应该 also mention, 然而, 那, in 这 研究, they had 人们 do a five-天 caffeine abstinence prior to being tested 与 300 milligrams 或 600 milligrams of caffeine. So the simple tool to extract 从 这 和 other 研究 like it is 那, if 你 want to experience the maximum alertness-promoting effects of caffeine when 你 ingest it early in the 天, 你 会 abstain 从 caffeine 对于 five 天 和 then ingest caffeine 90 to 120 分钟 之后 waking.

I 会 still hope 那 你 were doing all the other things 那 I described-- 早晨 sunlight, 运动, et cetera-- correctly. 但 regardless, it's 非常 clear 那 a five-天 abstinence 从 caffeine 然而 painful 那 可能 be 会 增加 the 表现-增强 effects of caffeine when 你 take caffeine on 那 sixth 天. Now, I'm sure many of 你 out there are saying, why 会 I ever want to abstain 从 caffeine 对于 five 天 in order to just get 这 six-天 表现-增强 effect?

Well, there are a couple of reasons 对于 doing 那. Perhaps 你're planning to travel to a new time zone, 和 你 want to use caffeine as a stimulant to stay up 期间 the 天 in the new time zone. 那's a somewhat unusual case. Others of 你 可能 be interested in the pro-身体表现 effects of caffeine. 我们'll talk 更多 关于 这些 in a little bit.

但 你 want to get the maximum 力量 增加 或 the maximum 耐力 增加 从 ingesting, in 这 case, 300 to 600 milligrams of caffeine. Well, in 那 case, abstaining 从 caffeine 对于 five 天 会 greatly exacerbate the pro-表现 effects of caffeine when 你 take it on 那 sixth 天, 尽管 admittedly, 那些 five 天 are 可能 to be pretty painful if 你're a regular caffeine user. Another variation on 这, 然而, 可能 be to have the amount of caffeine 那 你 ingest on a daily basis 和 then go back to 你的 regular 水平 of caffeine intake on 那 天 in which 你 need the caffeine to 确实 boost 你的 情绪, 能量, 和 表现.

Another reason why 你 可能 want to abstain 从 caffeine 或 减少 你的 caffeine intake 对于 a period of time 和 then go back to 你的 regular caffeine intake is simply to identify how much of an effect caffeine is 确实 having on 你的 overall 水平 of daily functioning 和 情绪. 这 was something 那 was actually covered in beautiful detail in a book by Michael Pollan all 关于 caffeine. It's available on Audible. I 确实 enjoyed 那 book.

It describes his experience 与 the decision to completely abstain 从 caffeine 对于 a period of months, 尽管 I confess 那 之后 hearing 那 book, what it basically made me want to do is 从不 quit drinking caffeine 因为 it sounded as if, at least my interpretation was, 那 even 之后 several 周 或 months of abstaining 从 caffeine, 那 he still fantasized 关于 the effects of caffeine. 但 he did mention 那, when returning to ingesting caffeine 之后 a period of long abstinence, 那 it had almost a-- let's not call it a psychedelic property, 但 it had such obvious effects on 情绪 和 alertness 和 feelings of well-being 那 it 确实 highlighted 对于 him the extent to which caffeine normally was allowing him to just function what he thought was normally.

So in other words, many of us don't even 确实 know what 我们的 normal basal 水平 of cognitive 和 physical functioning is 因为 我们're ingesting caffeine on such a regular basis. I confess 那, as much as I enjoyed 那 book 和 as intriguing as his description of caffeine abstinence 和 then the return to caffeine was, I don't intend to ever find out personally.

Now a 非常 good reason why 你 可能 want to abstain 从 caffeine 对于 a deliberate period of time 和 then return to caffeine intake is 对于 its 身体表现-增强 effects. 和 here 我们 可以 look to a 确实 interesting 研究. The title of which is "Time course of tolerance to the 表现 effects of caffeine." 和 what I like 关于 这 研究 is 那, while yes, it does say 那 abstaining 从 caffeine 和 then returning to caffeine intake 可以 增强 身体表现 in a 非常 具体的 way, it also says 那, if 你 take caffeine regularly, 你 可以 still see the 身体表现-增强 effects of caffeine.

尽管 they are not quite as robust as they 会 be had 你 abstained 从 caffeine. The design of the 研究 is pretty straightforward. They had 人们 either ingest 3 milligrams per kilogram of caffeine 对于 20 consecutive 天. Many 人们 are already doing 那, I realize, 但 they had 人们 do 那 或 ensure 那 they were doing 那. 或 others ingested a placebo 对于 20 天, so they abstained 从 caffeine 没有 realizing it.

Then 之后 那 20 天 of either ingesting caffeine 或 a placebo, their peak 表现 was measured in terms of aerobic output. 但 prior to 那 measurement, they had caffeine, OK? So it's 20 天 of caffeine 和 then a 21st 天 of caffeine 和 then the physical task on 那 21st 天. 或 it's 20 天 of abstinence 从 caffeine.

和 then on 天 21, 你 get caffeine, 和 你 get the same physical test. 和 what they discovered was 那 the ingestion of caffeine 增加了 peak 表现 in 这 aerobic output dramatically if 人们 had abstained 从 caffeine. 但 对于 人们 那 had consumed caffeine all the way 通过 up until 那 天, it still was effective to ingest caffeine on 天 21 但 not as effective as it 会 have been had they abstained.

和 in fact, the magnitude of what they call ergogenic effect, which is the pro-表现-增强 effect of caffeine, was higher on the 首先 天 than in subsequent 天 when they allowed 人们 to continue caffeine intake. So the takeaway 从 这 研究 is 确实 straightforward. If 你 want to get the maximum 身体表现-增强 effects of caffeine, 你 abstain 从 caffeine 对于 20 天.

Then on 天 21, when 你're going to do the physical thing, the task, 你 ingest caffeine 关于 30 分钟 to an 小时 之前 你 do 那 physical challenge. Now 20 天 of abstinence is going to be rough 对于 a lot of 人们. I certainly don't want to sign up 对于 这 研究. In which case, 你 可能 want to do five 天 of abstinence as 我们 talked 关于 之前.

和 then on 天 six is the 天 那 你 ingest caffeine 和 do the physical task. There are even some 研究 showing 那 你 可以 abstain 从 caffeine 对于 just 二 天, 对于 just 48 小时. 和, in particular, if 你 are a regular user of caffeine, 这 allows 你 to, on 天 三, ingest caffeine at the dose 那's appropriate 对于 你 和 do the physical, 或 I 应该 mention 心理表现 task 和 perform significantly better than 那些 那 have been taking caffeine throughout the entire period leading up to the challenge.

So 你 don't necessarily need to abstain 对于 20 天 in order to get the pro-表现 effects of caffeine on 天 21. 你 could do five 天 of abstinence prior 或 even 二 天 of abstinence prior. 或 if 那's intolerable to 你 as it is in my 心智, to me, to just 减少 你的 caffeine intake slightly 或 even perhaps have it if 你 可以 tolerate 那 in the 周 或 二 周 或 maybe even 三 周 preceding some physical 或 mental challenge.

Now again, 这 sort of implies 那 你're going up against a marathon, 或 你're going up against a series of long tests, maybe standardized tests in 一 天. There, I just 确实 want to point out 那 there is an abundant literature showing 那 人们 perform best on mental tests if they are in the state 那 they were when they studied 对于 那 material. Now in college, I knew a number of 人们 who took 这 to the extreme, thinking 那 if they were to 研究 under the effects of alcohol, 那 they 会 be best off consuming alcohol prior to taking exams.

和 it turns out to not be the case. Here 我们're talking, in particular, 关于 psychostimulant effects of caffeine 和 other compounds. So don't think 那 你 可以 drink 或 be under the influence of THC 和 then take-- when 你 研究 和 then take an exam under the same influence 和 do just as well as 你 会 had 你 not ingested anything. Please don't let 那 be the takeaway. 然而, do let it be the takeaway 那 caffeine's effects are made 更多 potent by a brief to not so brief period of abstinence prior to taking a dosage of caffeine.

和 then the final point to make is 那, if 你 are somebody who is not accustomed to drinking caffeine, meaning 你're hypersensitive to caffeine 或 你 don't regularly ingest caffeine, please do not ingest caffeine on the 天 of any 重要 mental 或 physical challenge 或 表现, 因为 what 你 会 find is 那 因为 你 are not caffeine-adapted, 你 会 experience changes in 你的 thermal regulation, in 你的 水平 of anxiety 和 jitteriness, 和 你的 水平 of 专注 那 could be 非常 detrimental to mental 或 身体表现. So 你 don't want to throw yourself in the deep end by ingesting caffeine if 你're not used to it.

和 I 应该 mention 那 对于 人们 那 are not accustomed to ingesting caffeine 或 are 非常 sensitive to caffeine. Even 25 to 50 milligrams of caffeine in the amount 那's found in, 对于 instance, a piece of certain types of chocolate 可以 actually cause anxiety. So be careful there. Here, I'm referring only to 人们 那 are accustomed 与 caffeine intake.

So what I recommend is to explore the ergogenic effects of caffeine 期间 你的 训练 和 then to make a decision 关于 what 你 可以 reasonably 和 reliably do in terms of abstinence 和 then pulse 与 caffeine on the 天 of the challenge. I get a lot of questions as to whether 或 not caffeine has 不同的 effects on the 神经系统 和 on 表现 in particular, depending on phases of the menstrual cycle. So I explored 那 in my 研究 对于 这 episode, 和 I found 二 研究 both of which 我们 会 reference in the show note captions.

The 首先 一 is entitled "Caffeine consumption 和 menstrual function." So it's actually the relationship between caffeine 和 menstrual function. 我们 会 do an entire episode 关于 the menstrual cycle 和 menstrual function. 但 the other 一 as it relates to 表现 was published in 2020 in the European Journal of Nutrition, which is "Ergogenic effects of caffeine on peak aerobic cycling power 期间 the menstrual cycle." 和 the basic takeaway of 这 研究 is-- frankly, a 非常 nice 研究, showed 那 quote, "Caffeine 增加了 peak aerobic cycling power in the early follicular, preovulatory, 和 midluteal phases of the menstrual cycle."

Thus, the ingestion-- 和 again, here they use 3 milligrams of caffeine per kilogram of 身体 mass 可能 be considered an ergogenic aid 对于 women who are in the menstrual cycle 期间 all 三 phases of their cycle. So keep 那 in 心智, women-- 对于 那些 of 你 那 are regular users of caffeine 或 你're using caffeine to 增强 身体表现, there does not seem to be any menstrual cycle phase-dependent effects of caffeine on 表现. 那 is, caffeine seems to 总是 增加 身体表现 regardless of the phase of the menstrual cycle 你 可能 happen to be in.

I'd like to touch on a little bit 更多 of the use of caffeine 对于 增强 心理表现. Yes, it is the case 那 ingesting 1 to 3 milligrams of caffeine per kilogram of 身体 weight in the 30 分钟 或 so prior to doing a memory task 或 sitting down to doing some studying 或 learning of any kind, physical 或 心理表现, of any kind is beneficial 对于 all the reasons 我们 talked 关于 之前, relate to 多巴胺 和 acetylcholine, et cetera. 但 it turns out 那 it is also the case 那 spiking 一's 肾上腺素 和 other so-called catecholamines-- so 这 会 be 多巴胺, 去甲肾上腺素, 和 肾上腺素-- 之后 a bout of learning 可以 greatly 增强 memory 对于 the information 那 一 was trying to learn. 那's right.

Spiking 你的 肾上腺素 之后 learning 可以 greatly 增加 memory 对于 the material 你're trying to learn. In fact, 这 is a practice 那 dates back centuries 和 was written 关于 in a beautiful Annual Review of Neuroscience on the biology of memory by James McGaugh, where he talks 关于 medieval practices of children being taught information 和 then being thrown literally 进入 寒冷 水 to stimulate the 释放 of 肾上腺素 和 那 增加 in 肾上腺素.

While the mechanism wasn't completely understood, it was understood 那 那 sort of shock to the 系统 从 the 寒冷 水 led to better memory 和 retention of the information 那 这些 children had been exposed to. 和 it turns out the exact same thing is true 对于 adults in the laboratory 或 kids in the laboratory. 和 here I'm not suggesting throwing anyone 进入 寒冷 水.

If 你 want to get 进入 寒冷 水, there's a reason 我们 call it 主动冷暴露 on the podcast is 那 it 应该 be deliberate 和 controlled by 你, not by somebody else. 和 if it's controlled by somebody else, 那 可能 be military screening 或 something. 但 here 我们're talking 关于 deliberately increasing 你的 水平 of 肾上腺素 和 other catecholamines, 多巴胺, 去甲肾上腺素, et cetera.

你 可以 do 那 certainly by 主动冷暴露 与 a 冷水淋浴 或 getting in up to 你的 neck in 寒冷 水 of any kind. 但 the other way to do 那 is to spike 你的 肾上腺素 by ingesting 1 to 3 milligrams per kilogram of caffeine 之后 sitting down to try 和 learn some material I confess 那, 更多 经常 than not, I use caffeine in the same way 那 most 人们 use it, which is OK. I'm going to sit down. I'm going to 研究 information 对于 a podcast 或 assemble some information 对于 a paper 或 grant, 和 I want to 专注.

So I 会 drink a cup of coffee at the beginning of 那 和 maybe even throughout 那 或 a couple of yerba maté at the beginning 或 throughout 那. 或 I'll sip on 一 或 both throughout trying to learn. 和 那 works quite well in terms of maintaining 专注 和 alertness 和 retention of information, 但 it is indeed the case. 那 is, the 研究 supports the fact.

和 I've experienced the fact 那, if I abstain 从 caffeine while I'm trying to learn something-- 但 then I drink caffeine immediately 之后. Somewhat surprisingly to me 但 certainly in a way 那's consistent 与 the 研究 literature, memory 对于 the information 那 I was focused on prior to ingesting 那 caffeine is much greater. 和 here I'm talking 关于 as a personal anecdote, 但 这 is actually what the 数据 point to both in animals 和 in humans.

和 if 你 think 关于 it, it makes perfect sense 因为 the way 那 the memory 系统 of the 大脑 are organized is 那 我们 go 通过 life experiencing things. 我们 encounter surprises both good 和 bad. 我们 go 通过 the motions of things both typical, mundane, exciting, 和 novel, 和 not novel. 和 then every once in a while, something 会 happen 那 会 spike 我们的 catecholamines.

多巴胺, 通常 if it's a positive surprise. 肾上腺素, which 可以 be associated 与 both positive surprise 或 positive events 和 negative events 或 surprises. 和 没有 fail, 增加 in the catecholamines tend to lock in memories 对于 things 那 preceded the 增加 in 那些 catecholamines. Again, the catecholamines being 多巴胺, 肾上腺素, 和 去甲肾上腺素, sometimes all 三 in combination, sometimes just 二 of 那些, sometimes just 一 of 那些, depending on the experience.

So it makes perfect sense 那 using caffeine at the end of a learning bout 会 增强 我们的 memory 对于 the information 那 我们 are trying to learn. So if 你 decide 那 你 want to try 和 extract 这 表现-增强 effect of caffeine, what I recommend 会 be to try 和 abstain 从 caffeine 对于 a 天 或 二 prior. 但 if 你 可以't, 你 just continue 与 你的 normal caffeine intake. 但 then when 你 sit down to 研究 或 learn something to not ingest any caffeine as 你 do 那 但 then afterward to ingest caffeine.

Now in theory, 你 could probably further 增强 the memory encoding effects of 肾上腺素 和 the other catecholamines by drinking caffeine 和 then taking a 冷水淋浴 或 doing 主动冷暴露 if 你 确实 wanted to 或 had the ability to 或 doing some sort of intense form of 运动. 和 我们'll talk in a moment 关于 how caffeine, 运动, 和 the 肾上腺素 系统 interact. 但 as a brief 但 relevant to side, brief bouts of intense 运动 ranging 从 10 to 50 分钟 或 so have been shown to 改善 memory 对于 information 那 一 was trying to learn prior to the intense 运动.

这 is work 从 Dr. Wendy Suzuki's lab at NYU as well as other laboratories, some of the work 那's being done at Stanford in the 心智, 身体 Laboratories. 和 我们的 laboratory points in the direction of 这些 kinds of effects as well. They all come back to the same general neurochemical theme, which is 那, when 我们 experience an 增加 in 这些 catecholamines 那 include 肾上腺素, 多巴胺, 和 去甲肾上腺素, the memory 系统 of the 大脑 flip on in a way 那 try to capture the information 和 the perceptions 和 the experiences 那 我们 were exposed to just prior to the 增加 in catecholamines 和 caffeine 但 also 运动 和 also 寒冷 水.

和, of course, any of 那些 alone 或 in combination all 增加 the 水平 of catecholamines, so it makes perfect logical mechanistic sense as to why 这 会 work. 和 in fact, it does work. If 你 want to remember 具体的 information, 你 可能 consider using caffeine as 你 move 通过 和 absorb 和 are exposed to 那 information. 但 你 可能 also consider using caffeine 之后 being exposed to 那 information 因为 研究 in animals 和 humans show 那 那 is a potent way to 增加 memory 对于 what 你 are just exposed to.

I 应该 mention 那 what I just described also pushes back on something 那 I know a number of 人们 perhaps have heard 关于 和 maybe even use, which is 这 notion of the nappuccino. I remember hearing 关于 这 a few years back. It was sort of trend, if 你 会. The trend involved drinking a cup of coffee 或 a double espresso 和 then going down 对于 a nap 通常 in the 下午 和 then waking up. 和 the idea was 那 the caffeine 会 hit 你的 系统 right at the time 那 你 awake 从 the nap 和 那 你 会 be better able to 专注 和 运动.

There are a couple of things 关于 那 practice 那 I don't like. 首先 of all, it implies, in most cases, 那 你're napping 和 ingesting caffeine in the 下午, which I realize 对于 many students 和 对于 人们 那 are comfortable staying up until the wee 小时 of the 夜间 和 then waking up late the next 天 可能 be compatible 与 their schedule. 但 again, 因为 of the sleep-diminishing effects of caffeine-- 和 我们 talked 关于 earlier.

I'm not crazy 关于 the idea of 人们 ingesting caffeine in the late 下午 in order to perform better in the late 下午. Far better 会 be to restrict caffeine intake to the early part of the 天 as 我们 talked 关于 earlier. The other reason is 那 the 数据 on things like non-sleep deep rest 和 naps in the 下午-- 和 again, the rule here is 那 你 don't have to nap.

但 if 你 want to nap, it's been shown 那 naps of 90 分钟 或 更少 或 non-sleep deep rest 方案-- 和 你 可以 find 那些-- 对于 instance, there's 一 与 me speaking. 你 just put NSDR Huberman 进入 YouTube. 你 可以 hear 那. It's completely zero cost. There are other NSDR scripts out there now, of course, if 你 prefer 那些, 那 那些 可以 all lead to 增加 in 一 of the catecholamines at least, which is 多巴胺.

那's been shown in a 确实 nice 神经递质 labeling 研究, not 从 my laboratory, 但 从 another laboratory, 但 also 可以 改善 情绪, 专注, 和 alertness on its own 没有 the need to ingest caffeine prior to going 进入 那些 states. 和 in fact, ingesting caffeine prior to a nap 或 ingesting caffeine prior to NSDR is most certainly going to 减少 the effectiveness of 那 nap 和 NSDR in restoring natural 水平 of alertness 和 专注 那 会 lead to the 表现-增强 effect. So I'm not such a fan of the so-called nappuccino, 尽管 if any of 你 out there have derived great benefit 从 it, definitely let me know 你的 方案 和 what 你've experienced.

Put it in the comment section if 你 会. I'd appreciate 那. There's another 非常 重要 和 potent use of caffeine 对于 增强 表现. 和 这 relates not just to the 多巴胺 和 肾上腺素 和 the arousal-inducing effects of caffeine. 和 it doesn't even just relate to the effect of caffeine on 增强 frontal lobe function.

It does include all 那, 但 it also includes 那些 reinforcing effects of caffeine 那 我们 talked 关于 at the beginning of the episode. 和 the best way to illustrate 这些 表现-增强 effects of caffeine 那 stem directly 从 its association 与 reinforcement is to highlight a 研究. 和 the title of the 研究 is "血液 多巴胺 水平 enhanced by caffeine in men 之后 treadmill running." 和 as the title suggests, 这 was carried out in men, 但 there's no reason to think 那 the same 结果 wouldn't also be present in women.

There are some sex-dependent effects of caffeine. I'll touch on just briefly at the end. 但 那些 are largely present in kids. 那 is, adolescents 和 teens as opposed to adults. So 这 研究 is 确实 interesting.

What they had 人们 do was run on a treadmill 和 either ingest caffeine-- again, 3 milligrams per kilogram of 身体 weight-- 或 to not ingest caffeine. 和 then they looked at 水平 of 多巴胺 和 other 神经递质 和 激素, such as prolactin 和 cortisol. 和 the basic takeaway is, as the title suggests, 那 运动, while on its own, 可以 增加 cortisol in healthy ways, provided it's not too intense 和 too long. A little note here, if 你 have trouble recovering 从 运动 或 你 want to continue to derive the benefits 从 运动, in general, best not to do high-intensity 运动 对于 longer than 75 分钟.

或 90 分钟 probably being the outer threshold. I realized 那 there are some genetic freaks out there 或 人们 那 are chemically assisted 那 可以 recover 从 非常 intense long bouts of 运动. 但 most 人们 don't do well 通过 long bouts of intense 运动 on a regular basis. 和 limiting their intense 运动 to 60 分钟 或 更少-- 那 doesn't include the warm-up-- is going to be beneficial.

See the episode on tool kit 对于 fitness if 你'd like details on 那. 运动 is known to 增加 水平 of 多巴胺, cortisol, 和 other catecholamines 和 神经递质 非常 potently 和 things like testosterone 和 estrogen in ways 那 我们 know are beneficial to us 和, of course, have all 这些 positive effects on the musculoskeletal 系统 和 cardiovascular effects. 但 unbeknownst to most 人们, ingesting 3 milligrams per kilogram of caffeine prior to 运动 further 增加 the 多巴胺 释放 associated 与 运动 specifically.

和 这 has 二 重要 effects. 首先 of all, 那 增加 in 多巴胺 is great 因为 it provides a long-lasting 增加 in 专注 alertness 和 motivation, not just 期间 the 运动, 但 also 之后 the 运动. 和 秒, it-- 那 is, caffeine 和 多巴胺 in combination-- act as a reinforcer to make the experience of 运动 和 the period immediate 之后 运动 更多 pleasant 和, in fact, reinforcing.

So in other words, 一 way to enjoy 运动 更多 和 to enjoy the activities 那 follow 运动 更多 和 to experience a genuine 增加 in 多巴胺 那's beneficial 对于 情绪 和 alertness is to ingest caffeine prior to 运动. Now 这 is 重要 因为 a number of 人们 out there are exercising, love 运动, love eating great, love doing all the things 那 are beneficial 对于 their health, 但 a number of 人们 out there 确实 don't like to 运动. 和 那 serves as a serious block 对于 their willingness 和 their consistency to 运动.

Ingesting caffeine gives us 能量 to 运动. It 增加 the 释放 of 神经化学物质 和 激素 那 are good 对于 us 期间 运动. 但 as I'm highlighting here, it also 增加 the reinforcement 通路 associated 与 运动. 那 is, it creates a positive feeling 关于 the general theme of engaging in 运动, 和 it creates a general positive experience of the things 那 follow 运动.

So I think 这, if nothing else is a call 对于 或 support 对于 the idea, 那 ingesting caffeine as a 表现-增强 tool makes perfect sense. 但 对于 那些 out there 那 don't enjoy 运动, in particular, certain forms of 运动, ingesting caffeine 可以 change 你的 relationship to 那 运动. In other words, make it 更多 positive, much in the same way 那 ingesting caffeine alongside a certain taste 那 会 otherwise be neutral 或 maybe even negative 可以 actually make the taste of 那 particular drink 或 food positive.

So again, 这 brings us back to the reinforcing properties of caffeine 那 are subconscious. It's not just 关于 the enhanced 表现 in the test 或 the enhanced 表现 on the treadmill 或 与 the weights in the gym. It's enhanced feelings of 情绪 和 well-being 那 are genuine 因为 of the effect of caffeine on certain 神经递质 和 激素 系统, 但 it also is creating an overall milieu of reinforcing all of the things 那 led in to occur 期间 和 occur 之后 运动.

I do want to point out something 那's 非常 重要 as it relates to combining things like caffeine 和 运动 in order to 增加 多巴胺. 这 is something 那 came up in the episode 那 I did on 多巴胺, motivation, 和 drive, which turns out to be 一 of 我们的 most popular episodes. Again, 你 可以 find 那 at hubermanlab.com 和 links to all formats 与 time stamps, et cetera.

这 also came up in the episode on ADHD 因为 of the relationship between ADHD 和 多巴胺. 和 那's 这 notion of 多巴胺 stacking. In the episode on 多巴胺, motivation, 和 drive, I pointed out 那, while there are a near-infinite number of things 那 可以 增加 多巴胺 释放, most notably positive surprise 或 positive anticipation 或 experiencing a win.

Certainly, there are compounds, both drugs of abuse, food, sex, 和 certain supplements 那 可以 增加 多巴胺 to varying 水平 和 to varying degrees, both healthy 和 unhealthy. 那's all contained in 那 episode on 多巴胺, motivation, 和 drive. 但 what I pointed out is 那, if 你 are somebody who tends to experience difficulty 与 motivation-- 那 so-called 多巴胺 stacking as I called it 可能 be something 那 你 want to avoid.

What's 多巴胺 stacking? 多巴胺 stacking 会 be combining a highly caffeinated 能量 drink 那 also includes the amino acid tyrosine, which is a precursor to 多巴胺, plus loud music plus getting yourself 确实 ramped up then an intense workout. All of 那 可以 be great if 你 do it every once in a while. 但 what 你 会 quickly find is 那 the extent to which 你的 多巴胺 peaks also dictates the extent to which 你的 多巴胺 会 drop 之后 那 peak. 和 when I say drop, I mean drop below baseline.

So a lot of 人们 find 那, if they stack a lot of things to peak their 多巴胺, then they experience a low, 和 it does take some time 对于 them to return to baseline. 和 I highly recommend not engaging in activities 或 consuming compounds 那 are in attempt to accelerate 那 return to baseline 因为 all it 会 do is drive 那 baseline lower 和 lower. So 这 requires being able to tolerate a drop in 多巴胺 baseline 对于 a period of time, et cetera.

Now the reason I'm bringing 这 up now in the context of 这 caffeine episode is I just described a 研究 in which using caffeine prior to 运动 增加 多巴胺 之后 运动. 和 so 你 可能 be saying, 尤其是 if 你 heard 那 earlier episode, wait, isn't 那 多巴胺 stacking? Aren't 你 encouraging me to stack my 多巴胺?

Well, in some sense, yes. 但 keep in 心智, I'm not suggesting 那 你 do 这 every time 你 运动. So just as in 那 earlier episode, I emphasized the fact 那, while stacking multiple stimuli-- caffeine 或 能量 drinks 和 music 和 et cetera-- 对于 运动 或 对于 mental work 或 对于 any experience 对于 那 matter is OK to do every once in a while 对于 most 人们, 你 don't want to get in the habit of doing it consistently every time 你 运动 或 every time 你 go out, 对于 instance.

和 so 你 确实 want to be cautious. 那 is, 你 want to protect 你的 both baseline 水平 of 多巴胺 和 你的 peak 水平 of 多巴胺. 那 said, 对于 人们 那 want to experience an 增加 in 情绪, alertness, 和 表现, 或 who want to condition themselves-- 因为 那's 确实 what it is. It's conditioning yourself by the reinforcing effects of 多巴胺 to 增加 你的 liking 或 maybe even 你的 loving of 运动.

Occasionally, using caffeine 或 frequently using caffeine prior to 运动 is fine 但 be 非常 careful. 和 by being 非常 careful, what I mean is pay 注意力 to how 你 feel in the 小时 和 天 之后 那 多巴胺 增加 wears off. So 对于 instance, if 你 ingest caffeine 和 then 运动 非常 intensely 和 你're feeling great afterwards 但 then eight 小时 later 或 the next 天, 你're feeling a little bit low, I suggest 你 don't go back 和 do the exact same thing right away.

I 会 give yourself a little bit of time to let 那 baseline of 多巴胺 return to normal. So again, stacking 不同的 things, chemical 和 behavioral, in order to 增加 多巴胺 可以 be done in a safe way 那's beneficial to 你, depending on 你的 goals. 但 be careful 关于 not stacking too many stimuli 对于 多巴胺 too 经常. 那's the key.

Early in the episode, I mentioned 一 可能 caffeine-consuming schedule 那 works 非常 well 那 doesn't fortunately subject 你 to long 20-天 bouts 或 5-天 或 even 2-天 bouts of abstinence. 和 那's the every other 天 schedule of caffeine. If 你 look at the half-life of caffeine 和 你 look at its effects on the 多巴胺 系统 和 its 表现-增强 effects 和 how a period of abstinence 可以, in fact, 增加 the 表现-增强 effects of caffeine-- 但 also take 进入 consideration 那 caffeine 可以 be habit-forming, 和 我们 可以 develop a sort of tolerance to caffeine.

Well then, what emerges 从 all of 那 is 那 being a person who consumes caffeine every other 天 可以 actually help 你 maximize most of the positive effects of caffeine 没有 subjecting 你 to the kind of misery 那 occurs if 你're accustomed to consuming caffeine every single 天 和 then suddenly go 进入 a 2 或 5 或 20-天 abstinence. So I myself have 从不 tried an every other 天 caffeine approach, 尽管 I'm considering doing it based on the literature 那 I've read. 和 I'm considering doing it in a 非常 具体的 way, which 会 be to only consume caffeine on the 天 in which I resistance train.

和 since I tend to do 那 关于 三 或 four 天 per 周 organized in a way 那's every other 天-- again, if 你 want to see the 运动 schedule 那 I follow, including cardiovascular 运动 和 weight 训练 和 all the reasons 和 rationale 对于 what I do 和 how it maps on to the scientific literature, relate to health span 和 lifespan, vitality, et cetera, 你 可以 find 那 at hubermanlab.com. 和 我们 had a tool kit 对于 fitness 那 ought to be posted to 我们的 website 之前 long. The every-other-天 schedule of caffeine intake, to me, seems like the most rational 一 if 一 wants to maximize on the 表现-增强 effects of caffeine 没有 suffering the effects of caffeine withdrawal 那 are associated 与 being a regular consumer of caffeine 和 then stopping caffeine intake, such as headache 和 irritability 和 so forth.

Not I nor anyone in my life wants me to experience 那些 effects, 和 I'm sure 你 don't want to experience 那些 effects 对于 你 either. So if 你're somebody 那 decides to try the every other 天 方案 或 你 are somebody who's already doing 那 方案, please let me know what 你的 experiences 与 那 are. At least by my read of the literature on caffeine 和 it's 表现-增强 effects 但 also the effects of caffeine on 神经递质 和 激素 系统, the every-other-天 caffeine schedule does seem to be the most rational 和 scientifically grounded 一 in order to maximize on all 那些 effects.

In addition to so-called 表现-增强 effects of caffeine, there are also the well studied 和 now fairly well mechanistically understood pro-health effects of caffeine. Now, here when I talk 关于 pro-health effects of caffeine, I want to be 非常 clear 那, if 你的 schedule of caffeine intake-- 那 is, 你的 timing of caffeine intake 或 anything else 对于 那 matter-- offsets getting regular high quality sleep of sufficient duration, well, then 你 are undermining the pro-health effects of 那 thing.

这 is true 对于 运动. 这 is true 对于 caffeine. 这 is true 对于 supplementation. 这 is true 对于 prescription drugs. Again, 你 don't want to be neurotically attached to the idea 那 你 have to get perfect sleep every 夜间 因为 那's simply not true 但 is absolutely the case 那 anything, whether 或 not it's good 对于 你 或 bad 对于 你 in the short term, 那 disrupts 你的 sleep 因为 of the timing in which 你're doing 那 thing is going to undermine 你的 immediate 和 long-term health 之前 long.

So 与 那 said, there are several well described health-promoting effects of caffeine ingestion. 和 once again, when I say caffeine ingestion, I'm referring to 那 1 to 3 milligrams per kilogram of 身体 weight dosage. There are 确实 nice 研究 showing 那 being a regular consumer of caffeine 可以 help offset some of the probability, some of the probability of developing Parkinson's 和 maybe Alzheimer's-related dementia as well.

这些 are not terribly controversial 数据 因为 of the fact 那 caffeine is known to 增加 the 释放 of 那些 catecholamines, 多巴胺, 肾上腺素, 和 去甲肾上腺素, as well as acetylcholine. All 那些 神经递质 和 neuromodulator 系统 are the ones 那 are known to be defective in Parkinson's 和 Alzheimer's, 尽管 there are other transmitter 和 激素 系统 那 are defective as well. There are beautiful reviews on the neuroprotective effects of caffeine 和 neurodegenerative diseases.

They're quite extensive. 和 I'll just refer 你 to 一 和 the references therein, 和 我们'll provide a link to 这 in the show note caption. So the title as the topic at hand suggests is the neuroprotective effects of caffeine 和 neurodegenerative diseases. 这 was published in 2016. I'm sure there have been other reviews since then, 但 it includes many, many quality references 和 研究, both in animals 和 in humans, pointing to the fact 那 具体的 enzymes 那 are associated 与 the health of, in particular, 多巴胺 neurons are made 更多 robust by regular ingestion of caffeine.

It also points to the fact 那 the 增加 in 多巴胺 受体 那 is induced by regular ingestion of caffeine 那 I referred to earlier is another way in which 多巴胺, 然而 many 多巴胺 neurons remain 大约 in 人们 与 Parkinson's 或 人们 who are aging 那 lose 多巴胺 neurons naturally, 那 多巴胺 可以 have its maximal effect 因为 of the 增加 in 受体 对于 多巴胺 那 caffeine induces. 和 there are other biological mechanisms 那 further support why caffeine ought to be neuroprotective, including its effects on the acetylcholine 系统, which is 一 of the major 系统 disrupted in Alzheimer's dementia.

So in other words, it makes perfect sense as to why caffeine 会 be neuroprotective. Caffeine has also been shown to diminish headache, particularly when taken in combination 与 aspirin. 和 那's 因为 of the effects of caffeine 和 aspirin on 血流. There's also 证据 那 caffeine 可以 provide brief 但 substantial relief 从 asthma.

So I wouldn't want 人们 to rely on caffeine as a lifesaving approach to an asthmatic attack. 那 said, 对于 人们 那 suffer 从 minor asthma, 那 caffeine intake-- again, of the dosages 那 我们 talked 关于 之前 has been shown to alleviate some of the major symptoms of asthma 对于 anywhere 从 一 to four 小时. 和 I know 这 is of relevance to a lot of 人们 out there. 因为 caffeine 增加 the catecholamines 和 in particular 因为 caffeine 增加 多巴胺 transmission in the prefrontal cortex-- 这 area of the 大脑 那's associated 与 专注 和 rule setting 和 context 和 task switching-- caffeine is known to 改善 专注 和 alertness, in particular, in 人们 who have symptoms of ADHD 或 other 注意力 和 专注 issues.

Now caffeine alone does not appear to be as potent 对于 the treatment of ADHD as are things like Ritalin, Adderall, modafinil, 或 modafinil 和 Vyvanse. If 你 会 like a sort of head by head comparison of prescription drugs, supplements, 和 things like caffeine as well as coverage of behavioral tools 和 nutritional tools, et cetera 那 可以 positively offset some of the symptoms of ADHD, please see the episode 那 I did on ADHD. Again, 那's available at hubermanlab.com in all formats.

但 那 said, caffeine does 增加 专注, 和 it does it 通过 a number of 不同的 mechanisms, not the least of which is to 增加 多巴胺 transmission in the forebrain just as a drug like Ritalin 或 Adderall 会, 尽管 not to the same extent as a drug like Ritalin 或 Adderall does. 之前 我们 close today, I do want to just briefly return to the reinforcing effects of caffeine 那 我们 talked 关于 earlier. 这 研究 on the honeybees 那 showed 那 bees prefer certain vectors 因为 they contain caffeine. Even though they are not aware 那 那些 vectors contain caffeine, they just come to like the feeling 那 那些 nectars provide them so much 那 they associate 那 in a subconscious way 与 the flowers themselves, 和 they come to like 那些 flowers.

或 human beings. 对于 instance, children 那 ingest caffeinated beverages come to adore the taste of 那些 beverages. 和 beautiful 研究 have been done 那 describe how children 和 adults truly cannot distinguish between the taste of a caffeinated 和 noncaffeinated beverage. 和 caffeine 可以 be placed 进入 本质上 any beverage in order to give us a preference 对于 那 beverage 或 food. In fact, the 研究 have been done 与 yogurt. If 你 put caffeine 进入 yogurt of 不同的 flavors-- even plain yogurt which most kids don't like-- they 会 come to prefer whatever flavor contain the caffeine even if then 你 remove the caffeine 从 那 flavor.

Now eventually, their preference 对于 那 flavor 会 be extinguished, 但 all of 这 is just to say 那 so many of the things 那 我们 like, whether 或 not it's coffee 或 tea 或 a given flavor of food 或 a given experience 或 even 运动, occur 因为 我们 ingest caffeine in conjunction 与 那些 activities. Now 这些 are not tricks 那 你的 神经系统 plays on 你. 这些 are real neurochemical-reinforcing effects.

和 I think 那 我们 会 all do well to think 关于 和 to leverage 这些 reinforcing effects much in the same way 我们 会 do well to think 关于 和 hopefully not leverage aversive effects of certain compounds, right? The simple way to put 这 is I 或 anyone could get 你 to dislike something, someone, 或 some place by making 你 feel slightly 更少 good, lower 情绪. I don't even have to make 你 feel nauseous 但 更少 good 之后 ingesting something 或 having a certain kind of interaction 或 being in a certain environment, 非常 straightforward to do 那, 因为 of the way 那 你的 神经系统 is wired 对于 conditioning.

然而, there's the positive side of all 这, which is 那 it's 非常 straightforward to reinforce the experience of a given food, including its taste, 但 all the context 大约 it, the container, the texture, the 人们 你 consume it 与, where 你 consume it, et cetera. 对于 instance, I wonder why 我们 are not pairing caffeine 与 broccoli. 和 here I'm not suggesting 那 人们 actually do 那 experiment 或 play 那 trick on 人们, 但 你 have to sort of imagine 那, if caffeine is 这 incredible reinforcer of all sorts of things, in particular, things 那 我们 ingest 和 会 want to ingest 更多 of if it's paired 与 caffeine, well then, 你 actually 可以 use caffeine as a tool to 增加 reinforcement of 不同的 things.

和 你 可以 avoid caffeine as a way to further reinforce things 那 你 会 like to stop. 和 here I'd like to just give the example of sugar cravings. A lot of 人们 ask me, how do I avoid sugar cravings? I've talked 关于 the use of L-glutamine 对于 那. I've talked 关于 making sure 你're getting enough essential fatty acids 和 essential amino acids as a way to 减少 sugar cravings.

Please note, 然而, 那 if 你 are somebody who likes to have 你的 sugar, whether 或 not it's a piece of chocolate 或 你的 dessert, et cetera-- I'm not saying 那's bad, 但 if 你're trying to 减少 你的 sugar cravings, ask yourself, are 你 ingesting sugar along 与 caffeine? Could be the caffeine contained in 那 sugar-containing food like chocolate. 或 it could be 那 你're having a cup of coffee along 与 你的 pastry, 和 then 你're struggling 与 sugar cravings.

Well, think 关于 it. 你're not just being reinforced by the sugar 和 the effects of sugar on 多巴胺 which are real 和 both conscious 和 subconscious 通过 the gut to the 大脑 多巴胺 系统 和 direct on the 大脑 多巴胺 系统. 但 by coingesting caffeine, 你 are also further 增强 the reinforcing effects of sugar. The flip side to all of 这 is 那 你 could use caffeine as a way to 增加 你的 appetite 对于 certain things.

I actually know somebody. I won't reveal who 这 person is, 但 they are quite prominent podcaster who ingests 125 to 150 milligrams of in tablet form along 与 herbal tea 和 use 这 as a way to develop a preference 对于 herbal tea 因为 they found 那 coffee was giving them other effects 那 weren't good 对于 them. So it works quite well in animals, 和 it works quite well in insects. 和 it works quite well in humans.

I suppose animals, insects, 和 humans are all animals at the end of the 天, so no surprise there. 但 it all underscores the extent to which caffeine is an absolutely fascinating molecule. I mean, its ability to offset the sleepiness 系统, if 你 会, 这 adenosine 系统, 和 to control 我们的 schedules in 那 way to 本质上 take a withdrawal against the bank 那 is adenosine 和 then pay 那 back later in the form of getting sleepy later as opposed to when 我们 want to be alert, its ability to 增强 专注, alertness, 和 情绪.

和 if taken 之后 trying to learn something 和 remember it, to 增强 memory, 尤其是. 和 its ability to 增加 VO2 max, 增加了 力量. 我们 didn't even talk today 关于 it, 但 I'll just briefly mention 那 caffeine ingested in the sorts of doses 我们 talked 关于 earlier. 因为 its effects on the neuromuscular 系统 和 the calcium 系统 associated 与 neuromuscular exertion 和 fatigue 可以 增加 peak power output 和 肌肉 contractability.

It's 增强 表现 there as well. 和, of course, caffeine does a number of other things just generally related to overall 和 basal 水平 of 情绪 和 alertness, not the least of which are 这些 增加 in 多巴胺. So caffeine is 确实 an incredible molecule. It's affecting all 这些 various 神经递质 系统 但 not haphazardly. It's increasing 多巴胺 和 acetylcholine in the forebrain to 增加 注意力.

It's 减少 fatigue. It's improving mental 和 身体表现 对于 some obvious 和 some not so obvious reasons. 和 what I think is among the 更多 miraculous 和 powerful effects of caffeine, it is a potent, potent, potent reinforcer of things, foods, 人们, 和 experiences. 和 it's 一 那 你 可以 leverage in any direction 那 你 like once 你 understand the way 那 caffeine exerts 那些 reinforcing properties.

So today, I've 确实 tried to cover as much as I could 关于 the mechanisms of caffeine action in the 大脑和身体, as well as tools 和 schedules 和 dosages in which 你 可以 leverage caffeine in order to meet 你的 身体表现, 心理表现, 和 frankly 心理健康, 和 overall health goals. If 你're learning 从 和/或 enjoying 这 podcast, please subscribe to 我们的 YouTube channel. 那's a terrific zero-cost way to support us.

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So again, it's Huberman Lab on all social media platforms. 期间 today's episode 和 on many previous episodes of the Huberman Lab 播客, 我们 discuss supplements. While supplements aren't necessary 对于 everybody, many 人们 derive tremendous benefit 从 them 对于 things like sleep, 激素 augmentation, 和 专注. If 你'd like to see the supplements discussed on various episodes of the Huberman Lab 播客, please go to livemomentous.com/huberman.

我们 partnered 与 Momentus 因为 they are extremely high quality, they ship internationally, 和 they formulated supplements in the precise ways 那 are discussed as optimal to take 对于 various outcomes here on the Huberman Lab 播客. If 你 haven't already subscribed to the Huberman Lab 播客 newsletter, it is a monthly newsletter 那 includes summaries of podcast episodes as well as tool kits, all of which are completely zero cost. All 你 have to do is provide 你的 email to sign up. 我们 do not share 你的 email 与 anybody.

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和 你 可以 also access any of the previous newsletters 那 我们've 释放了, including the tool kist 对于 sleep, 对于 fitness, 主动冷暴露, 和 so on. By going to hubermanlab.com, go 进入 the Menu, go 进入 Newsletter, 和 there 你'll see 那些 as immediately downloadable PDFs. Thank 你 对于 joining me 对于 today's discussion 关于 caffeine, both its mechanisms, 和 its many powerful uses. 和 last 但 certainly not least, thank 你 对于 你的 interest in science.

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