Using Play to Rewire & Improve Your Brain

The episode opens with the host introducing himself as Andrew Huberman, a professor of neurobiology and ophthalmology at Stanford School of Medicine, and setting out the topic as the biology, psychology and utility of play. He grants that play is usually associated with children's games and childhood development, whether organized or spontaneous, but argues that adults need to play too. What he calls "the power of play" lies in its ability to change the nervous system so that people perform many activities better, not only play activities.

He also frames play as a way to try out new ways of being in work, in relationships and in one's relationship to oneself. He previews findings that taking on different identities within the same game or form of play supports more creative and dynamic thinking, and he links this to becoming better leaders, workers, students and learners, and happier people. These are presented as topics to be covered later; this section states the claims without yet giving the studies behind them.

A further preview concerns attention. The host says that learning to play properly can improve focus and is an active area of research for treating attention-deficit/hyperactivity disorder (ADHD), and that children who do not get enough play during certain stages of childhood are more prone to develop ADHD. He adds that everyone, with or without ADHD and regardless of how much play they had as children, can engage and grow the neural circuits involved, at any stage of life. The supporting data for the ADHD link is promised rather than presented in this part of the episode.

Before turning to play, the host describes a study published in Scientific Reports, a peer-reviewed Nature Press journal, with first author Honma, titled "Reading on a smartphone affects sigh generation, brain activity, and comprehension." He presents it as a peer-reviewed answer to a question he is often asked: what phones, tablets, computers and video games are doing to our brains.

According to his summary, the study involved 34 healthy individuals who read material either on a smartphone or on printed paper or a book. Comprehension was much poorer on smartphones than on paper. Ordinary breathing patterns did not differ between the two conditions. The difference was in one specific feature of breathing: physiological sighs.

He explains the physiological sigh by referring to an earlier guest, Professor Jack Feldman of the University of California, Los Angeles, an expert on breathing and its relationship with the brain. Roughly every five minutes, asleep or awake, people take a big deep inhale, often a double inhale, followed by a long exhale. The host says that unless something is severely wrong with the brain stem, everyone does this. The sigh reopens the hundreds of millions of small air sacs in the lungs, the alveoli, bringing in more oxygen, and the long exhale offloads carbon dioxide. He adds that he has encouraged people to use the sigh deliberately to reduce stress quickly, and that his lab studies physiological sighs and finds them effective for fast stress reduction.

The study's finding, as he describes it, is that reading on a smartphone suppresses physiological sighing without people noticing. He separates this from so-called email apnea, in which people hold their breath while emailing or texting. In the smartphone case, he says, the brain gets too little oxygen and does not offload enough carbon dioxide. The study also found that the prefrontal cortex, involved in focus, attention and learning, becomes hyperactive, which he describes as "a kind of desperate attempt to focus."

On mechanism, the host connects the result to his own research interests: how the size of the visual window relates to autonomic function, or internal state. Narrowing the visual window, as happens when looking at a small phone, seems to suppress the breathing apparatus. Physiological sighs are controlled by neurons in the brain stem's parafacial nucleus, discovered by Feldman, so he reasons there must be some pathway by which a narrowed visual window suppresses those neurons. He states plainly that "we don't know yet how this happens." The mechanism is therefore a hypothesis, not a demonstrated finding.

He draws two practical options from this. One is to remember to do physiological sighs about every five minutes while reading or texting on a smartphone. The other is to read material that really matters, or that must be recalled later, on a larger screen or, preferably, on paper or in books. He says this applies to tablets and computer screens too, but especially to smartphones of any screen size.

He ties the study to the many questions he receives about ADHD and difficulty focusing. He accepts that the common explanations, constant streams of videos and emotionally distressing content online, are probably true in many cases. His point is that this study suggests a separate factor: regardless of content, the size of the screen itself strongly affects the ability to learn and remember. He presents this as a feature of how visual and respiratory circuits evolved, joking that he "wasn't consulted at the design phase."

Turning to play, the host says he expected his research to turn up mainly papers mapping which brain areas control play. That literature exists and he will discuss it, but he argues the more important questions are what play is for, why we play when young, and why we play less as we age. He notes that people vary along a continuum from serious to playful. Some people enter a social setting with a playful, even mischievous quality and treat it as a chance for novel interactions. He places himself among those who instead tend to assess a new environment, saying he is not especially spontaneously playful, though more so around certain people.

He reports that all young animals, humans included, are more playful and engage in more spontaneous play early in life than later. He uses this to argue that play is about far more than games: it is how we test and expand our potential roles in all kinds of interactions.

The central biological claim of this section is that play is homeostatically regulated. Homeostasis refers to biological systems keeping themselves in balance. He gives examples: long wakefulness leads to a stronger drive to sleep, going without fluids increases thirst, and the same holds for food and most motivated behaviors. He acknowledges exceptions, such as feeling groggy after oversleeping, but says the general pattern holds.

He credits much of the understanding of the biology and psychology of play in animals and humans to the late Jaak Panksepp, nicknamed "the rat tickler." Panksepp found that rodents and many other animals produce laughter in response to tickling, cannot tickle themselves, and tickle one another. Most non-human animals laugh at ultrasonic frequencies too high for humans to hear, so with the right devices Panksepp and colleagues isolated rat laughter, and later kitten and puppy laughter were identified. The host also says that what a dog owner might hear is not the dog laughing.

Panksepp also found that when animals, including children, are kept from playing for a time, they play more once given the chance, much as food restriction leads to eating more later. The host argues this matters because it places play not among recently evolved higher-order functions but deeper in the brain, involving ancient structures such as the brain stem, and he says that is in fact the case.

The host says play arises from connections among many brain areas, with a key one being the periaqueductal gray (PAG), a brain stem region near where the brain transitions into the spinal cord. The PAG is rich in neurons that release endogenous opioids, meaning opioids the body makes itself, such as enkephalin. He distinguishes these from the drugs behind the opioid crisis.

According to the host, play triggers small releases of these endogenous opioids in both children and adults, far less than one would get from taking exogenous opioids. He describes exogenous opioids as potentially very hazardous, with high addiction and overdose potential, while acknowledging they have clinical uses.