#77 – AMA #2 with sleep expert, Matthew Walker, Ph.D.: short sleep mutants, optimal sleep environment, sleep apnea, & rapid fire questions
In this AMA, Dr. Matthew Walker, Professor of Neuroscience and Psychology at UC Berkeley, answers listener questions on sleep. Topics include genetic short sleepers, optimal sleep positions and temperature, effects of caffeine and sex on sleep, and sleep apnea.
Deep Dive Analysis
6 Topic Outline
Banter and Reflections on Car Racing Experience
Understanding the DEC2 Genetic Mutation and Short Sleepers
General Sleep Needs and Age-Related Sleep Changes
Importance of Different Sleep Stages: Rat Deprivation Studies
The Role of REM Sleep in Survival
Inquiry into Optimal Sleep Positions
3 Key Concepts
DEC2 Genetic Mutation
A rare genetic mutation (D-E-C number two) found in a tiny fraction of the population. Individuals with this gene are 'short sleepers' who can function on less sleep, typically around 6.25 hours, possibly due to a more efficient sleep system, particularly in clearing adenosine.
Adenosine
A wake-promoting chemical that naturally builds up in the brain during wakefulness, leading to feelings of sleepiness. Part of the function of sleep is to clear out this accumulated adenosine from the system.
Sleep Deprivation (Rat Studies)
Studies on rats demonstrated that total sleep deprivation led to death in about 9-11 days, indicating sleep is as essential as food for survival. Furthermore, selective deprivation of REM sleep caused death almost as quickly as total sleep deprivation, suggesting REM sleep is critically life-essential.
4 Questions Answered
The DEC2 mutation is a very rare genetic variant that allows individuals to naturally sleep less than the general population, typically around 6.25 hours, without apparent harm, possibly due to more efficient clearance of wake-promoting chemicals like adenosine.
The majority of the population needs between seven and a half to nine and a half hours of sleep, though this can be affected by age and other physiological factors.
As people age, parts of the brain responsible for generating sleep, particularly deep sleep (like the medial prefrontal cortex), atrophy more quickly, making it physiologically harder to generate the needed sleep.
Based on rat studies, REM sleep appears to be more life-essential than deep non-REM sleep, as rats deprived only of REM sleep died almost as quickly as those totally deprived of all sleep.
7 Actionable Insights
1. Aim for 7.5-9.5 Hours Sleep
Strive to get between 7.5 and 9.5 hours of sleep per night, as this is the optimal range for the majority of the population based on sleep studies.
2. Don’t Assume Short Sleeper Gene
Avoid assuming you are a genetic ‘short sleeper’ (DEC2 carrier) who can thrive on minimal sleep, as this mutation is extremely rare (a fraction of a percent of the population) and most people require significantly more sleep.
3. Align Bedtime with Natural Rhythms
Consider aligning your bedtime with natural rhythms, aiming for an earlier bedtime (e.g., 9-9:30 PM) rather than midnight, to promote longer sleep duration and harmony with the body’s natural edicts.
4. Prioritize All Sleep Stages
Ensure you are getting all stages of sleep, including deep non-REM and REM sleep, as every stage is essential for life support and serves a critical function that evolution has preserved.
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5 Key Quotes
The probability that you are a DEC2 carrier is very low. It's a fraction of a percent of the population right now. So you're far more likely to be struck by lightning in your lifetime, it turns out statistically, than to have this gene.
Matt Walker
Sleep is just as essential as food in terms of life support.
Matt Walker
It's such a fragile, idiotic state to be in this thing called sleep, that if there was any stage of it that could have been weeded out in the course of evolution, Mother Nature would have done away with it hundreds of thousands, if not millions of years ago.
Matt Walker
You are present in that moment and there is nothing else. There's nothing else behind you in terms of recollection. There's no prospection forward in terms of thinking about the future.
Matt Walker
There are only three sports, bullfighting, motor racing, and mountaineering. The rest are all games.
Peter Attia