AMA #7: Cold Exposure, Maximizing REM Sleep & My Next Scientific Studies

This ask-me-anything episode opens with a question many people who use deliberate cold exposure ask: can a cold plunge or cold shower make you catch a cold or otherwise get sick? The host adds a related question he says he gets "all the time": should you do deliberate cold exposure at all if you already have a sniffle, a cold or the flu? He says he will answer both, and will also cover research on how deliberate cold exposure may boost the immune system.

His short answer to the first question is hedged. As long as a session lasts no more than about five or six minutes at a stretch, he says you probably will not get sick "directly from the deliberate cold exposure." He notes that most people do about one to three minutes, sometimes five or six, and that those "really pushing it" may go up to 10 minutes. Afterward, people usually get dressed, use a sauna or take a hot shower before getting on with their day or going to sleep.

He extends this to sessions of one to 10 minutes followed by warming up, saying he "can't see how the deliberate cold exposure itself would enhance your susceptibility to getting sick." He also adds a safety caveat: people who aren't used to cold should not start with 10-minute sessions, but should begin with shorter ones.

The more important factor, he argues, is the environment you are in. He points to "an enormous number of studies" on how colds and other viral and bacterial infections spread. These include controlled laboratory studies where researchers tightly control a room's humidity and temperature. Summarizing that body of data, he says that "cold, dry air does seem to increase our susceptibility to viral and bacterial infections."