October 28, 2019


#77 – AMA #2 with sleep expert, Matthew Walker, Ph.D.: short sleep mutants, optimal sleep environment, sleep apnea, & rapid fire questions

Read Time 30 minutes

In this special episode, Matthew Walker returns for his second AMA episode where he provides his expert insight on numerous sleep-related questions directly from listeners. He answers a wide range of questions from the gene that causes the short sleeping phenotype, to the ideal sleeping position, to the optimal temperature for best sleep, to how fasting affects sleep, plus a full dissertation on sleep apnea, and much, much more. If you’re a subscriber, you can now listen to this full episode on your private RSS feed. If you are not a subscriber, you can learn more about the subscriber benefits here.

We discuss:

  • DEC2—A genetic mutation that produces a short sleeping phenotype [11:00];
  • What is the best position to sleep in? [22:45];
  • Should you consider a “sleep divorce” with your partner? [27:00];
  • The challenge of kids wanting to sleep in bed with their parents [28:45];
  • Is there an ideal type of pillow? [32:30];
  • Any data on hammock sleeping? Should adults be rocked to sleep like a baby? [34:45];
  • The optimal room temperature and body temperature for the best sleep [38:30];
  • Do humidifiers help? [50:40];
  • How do high altitudes affect sleep? [53:15];
  • What is the data on weighted blankets (e.g., the Gravity blanket)? [57:00];
  • Caffeine—How much, and in what way, does it affect sleep? [58:15];
  • How does sexual activity relate to sleep quality? [1:04:00];
  • Should we be sleeping in two phases? First sleep & second sleep? [1:06:30];
  • Napping—Is there ideal duration? Should we be napping or not? [1:08:30];
  • Advice for new parents dealing with sleep deprivation [1:12:00];
  • Understanding your sleep chronotype [1:16:15];
  • If you drink too much alcohol in a given night, is there anything you can do to make sure your sleep isn’t wrecked? [1:20:45];
  • How postmenopausal women can manage their sleep problems with (and without) hormone replacement therapy [1:23:00];
  • Could a daily practice of Wim Hof’s breathing method help or hinder quality of sleep? [1:29:15];
  • Why do some people paradoxically feel more tired the more they sleep? [1:31:15];
  • Sleep apnea—How to know if you have it, the different types, the causes, and helpful resources [1:33:15];
  • Is there such a thing called “sleep eating”? [1:45:00];
  • If Matt was “sleep czar”, what changes would he make to society to improve sleep? [1:46:15];
  • Catch up sleep: Explaining the difference between retrospective damage and prospective benefit [1:48:45];
  • Does poor sleep really speed up the aging process? [1:50:30];
  • Is medicated sleep better than no sleep? [1:53:00];
  • Does vivid dreaming disrupt the sleep cycle? [1:56:45];
  • Is there potential benefit to using “binaural beats” or some type of sound to induce better sleep? [1:57:45];
  • How is sleep affected by fasting and time-restricted eating? [1:59:45];
  • Is there any evidence that polyphasic sleep (e.g., “Uberman”) works? [2:03:30]; and
  • More.

DEC2—A genetic mutation that produces a short sleeping phenotype [11:00]

DEC2 mutation

  • People with this mutation are the acclaimed “short sleepers”
  • They don’t sleep as much as most people (or as much as most people should be sleeping)

Does this sound like you?

  • Many people think, “wow, I only get 5 hours of sleep and feel fine, this must be me”
  • Matthew cautions, it’s only a fraction of a percent of people who have this gene mutation
  • You are more likely to get struck by lightning than to have this gene mutation

So how much sleep do they need?

  • Some think 5 hours is all they need, however…
    • When you bring these people to the lab and set up ideal sleeping conditions…
    • They sleep about 6.25 hours
  • An important thing to point out is that the average person sleeps at 6.5 hours per night
    • And many people get much less than that
    • And they are NOT the DEC2 mutants
  • When you take the average population and put them in a lab…
    • They will sleep between 7.5-9.5 hours per night
    • Why the big range? ⇒ probably due to age difference in the general population

Why we don’t sleep as much or as well as we get older?

  • As we get older, even though we may need as much sleep as we did when we were younger…
  • Physiologically we just can’t generate that sleep that we need

Why can’t we?

  • Firstly, as we age, part of the brain atrophy as a quicker rate than others
  • Particularly the deep sleep generating areas ⇒ the medial prefrontal cortex
  • (Trick: Take your thumb, stick it between your eyes, raise it up about an inch and a half, and you’re right there. That’s your medial prefrontal cortex.)
  • That part of the brain atrophies quickly
  • It also accumulates beta amyloid most significantly and early on

How much sleep does a young, healthy person need?

  • If you take away electricity and only expose people to natural light, their sleeping habits will change
  • No electricity, no phones, etc.
  • Two things tend to happen
    • 1) They sleep almost 9 hours per night
    • 2) They go to bed around 9:30 pm (even people who say their bedtime is typically 11pm or later)

Back to the DEC2 mutation people

Are there any health consequences of having the DEC2 mutation?

  • We don’t know the answer yet for 2 reasons:

  1) Because we haven’t known about the gene for long enough to look at long term data

  2) There is just so few of these people to make any statically meaningful conclusions

Do they lose more sleep from one sleep stage vs. another?

{end of show notes preview}

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Matthew Walker Ph.D.

Dr. Walker earned his degree in neuroscience from Nottingham University, UK, and his PhD in neurophysiology from the Medical Research Council, London, UK. He subsequently became a Professor of Psychiatry at Harvard Medical School, USA. Currently, he is Professor of Neuroscience and Psychology at the University of California, Berkeley, USA. He is also the founder and director of the Center for Human Sleep Science.

Dr. Walker’s research examines the impact of sleep on human health and disease. He has received numerous funding awards from the National Science Foundation and the National Institutes of Health, and is a Kavli Fellow of the National Academy of Sciences.

Dr. Walker is the author of the International Bestseller, Why We Sleep. It has a singular goal: to reunite humanity with sleep.

In addition, Dr. Walker is an internationally recognized speaker, a successful entrepreneur, and a Sleep Scientist for Google.



Center for Human Sleep Sciencehttps://www.humansleepscience.com/

Matthew’s publicationshttps://www.humansleepscience.com/p-u-b-l-i-c-a-t-i-o-n-s

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  1. I met someone in university that slept only 2 hours a night. I found out when I was talking to his roommates, and I asked I don’t know how he does it – school full time, full time job and he goes to the gym everyday… they said “he only sleeps two hours a night! BUT when he sleeps he is in like a coma, you can’t wake him up. We will slap him and he won’t wake up.” I was like wtf… well he must have this mutant gene you speak of. He never seemed tired or sick, this guy was sharp and jacked. Last I heard he moved to Finland.

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