Matthew Walker, PhD: Sleep is the Boss of You – Bulletproof Radio

Check out the Bulletproof Radio Episode Page & Show Notes

Key Takeaways

  • “The less and less you sleep, the higher and higher your mortality risk… and the higher your risk for most of the diseases killing us in the developing world”
  • There is no single major system within the body or brain – cardiovascular, reproductive, thermoregulatory, metabolic, etc. – that isn’t optimally enhanced by sleep when you get it or detrimentally impaired when you don’t get enough
  • REM sleep is essential for emotional well-being
    • “REM sleep is overnight therapy”
  • You need to drop your core body temperature by 2-3 °F in order to get to sleep
  • One hour of iPad reading before bed has been shown to blunt the amount of melatonin that’s released by 50%
    • It also delayed the peak of melatonin by 3 hours
  • REM sleep is dominant in the last half of your sleep cycle (deep sleep is dominate in the first half)
    • If you typically get 8 hours of sleep and on one night get 6 hours, you lost 25% of your total sleep, but you may have lost 80-90% of your REM sleep
  • Early school start times are detrimental for kids when it comes to their ability to learn

Products Mentioned

  • In order to facilitate the release of melatonin, you might find it useful to wear blue light blocking glasses 1-2 hours before going to bed
  • Another hack – install Phillips Hue light bulbs in your house which change color to red light in the evening (which isn’t harmful to melatonin production)
  • Aim to sleep in as dark of an environment as possible
  • Dave has found Life Cykel’s Lions Mane Liquid Extract increases his REM sleep
    • He takes 7 dropper fulls every night

Intro

  • Dr. Matthew Walker (@sleepdiplomat) is the author of Why We Sleep (which Dave highly recommends) and a Professor of neuroscience and psychology at the University of California, Berkeley
  • Check out the Podcast Notes from Matt’s MANY podcast appearances:
  • The Bulletproof Radio Cool Fact of the Day
    • One night of poor sleep activates genes that are related to biological aging in older adults
      • This, in turn, increases risk of chronic disease

“We’re in the midst of a catastrophic sleep loss epidemic”

  • Within the last 100 years, humans have begun sleeping 15-20% less
  • The state of affairs:
    • In the 1940s, the average American adult was sleeping 7.9 hours/night
    • Nowadays – it’s 6.5 hours/night
      • In Japan, it’s 6 hours 22 minutes
    • (this is the case across all developed nations)

How do we know 6 hours of sleep isn’t enough?

  • Dave recalls a study that concluded adults who sleep 8 hours/night die more of all causes compared to people who sleep 6.5 hours/night
  • “The less and less you sleep, the higher and higher your mortality risk… and the higher your risk for most of the diseases killing us in the developing world”
    • But once you get more than 8.5-9 hours of sleep, your mortality risk then “increases significantly”
      • Why is this the case? – This uptick seems to be caused by people who are very sick (those who have cancer or an infectious disease)
        • “Sleep is THE best health insurance policy and best healing process we know of”
        • So – these people were likely sleeping more to cure/because of their sicknesses 
  • If sick people need more sleep, do healthier people need less sleep?
    • There is no single major system within the body or brain – cardiovascular, reproductive, thermoregulatory, metabolic, etc. – that isn’t optimally enhanced by sleep when you get it or detrimentally impaired when you don’t get enough
      • Just because your immune health is good doesn’t mean your reproductive/cardiovascular system doesn’t need sufficient sleep

Is there such a thing as getting too much sleep?

  • In short, yes
    • It’s no different than food, oxygen and water
      • You can overeat
      • You can overhydrate
      • You can die of too much oxygen
  • But MOST PEOPLE are far on the other side of the spectrum

Sleeping 6 Hours in an Airport vs. 6 Hours in a Cave

  • When sleeping in a noisy or unfamiliar environment, your sleep quality takes a hit
  • Sleep quality = 
    • How continuous your sleep is (AKA whether your sleep is frequently broken up throughout the night)
    • The depth of your sleep (AKA the amount of deep and REM sleep)

REM Sleep is More Important Than You Think

  • “REM sleep is more important for your mortality [than deep sleep]”
  • A sleep study from the 80s deprived rats of sleep until they died:
    • There were 3 groups:
      • One group was totally sleep deprived
      • The second group was deprived of non-REM sleep (AKA deep sleep)
      • The third group was deprived of REM sleep
    • Findings:
      • The first group died quickest (about as quick as you would from food deprivation)
      • The third group died almost as quickly as the first group
      • The second group took ~60% longer to die
  • The history of REM sleep:
    • When we as hominids left the trees and moved to the ground, the amount of REM sleep we started getting shot up dramatically
    • Humans get 2x the amount of REM sleep compared to any other mammal
  • REM sleep is essential for emotional well-being
    • “REM sleep is overnight therapy”
    • Dream sleep is the only time during the 24 hour period when the brain stops producing a stress-related chemical called noradrenaline (aka norepinephrine)
      • During this time, the emotional and memory centers of the brain are ~30% more active than when you’re awake
        • For this reason, dreaming is essentially divorcing the emotion from the memory
          • Expanded – The brain is reactivating and reprocessing the emotional experiences of the prior day in a neurochemical state that is “safe,” devoid of any stress neurochemistry
          • So when you wake up, you remember the emotional memories, but you’re left with a memory of an emotional event, that is no longer itself emotional
    • People with PTSD do not experience this shut down of noradrenaline release (this inhibits the normal processing of traumatic experiences)
    • “It’s not time that heals all wounds, it’s time and REM sleep”
  • “Alcohol is one of the best ways that we know of to block your dream sleep”
    • Over time, if you block REM sleep long enough, it bursts onto the scene when you’re awake – this is known as delirium tremens (a bleed over of REM sleep into the waking state)

The Ideal Night of Sleep

  • The numbers:
    • 25-30% deep sleep
    • 20-25% REM sleep
    • 45-50% light sleep (stage 2 non-REM sleep)

Is light sleep = junk sleep?

  • NO
  • Light sleep is filled with “sleep spindles” (short bursts of electrical activity which are essential for learning and memory function)

Which stage of sleep is most important?

  • They’re all important
  • The fact that all of the sleep stages survived millions of years of evolution tells you they all serve a purpose

Sleep and Temperature

  • You need to drop your core body temperature by 2-3 °F in order to get to sleep
    • This is why you’ll find it easier to fall asleep in a room that’s too cold compared to too hot
  • One study found that by having people wear temperature controlled suites, in which only the feet and hands were warmed, cause the core body temperatures of the participants to drop
    • Why? – Blood is drawn away from the central part of the body
    • (For this reason, you might find it useful to wear socks and gloves to bed in order to help drop your core body temperature)
  • As background:
    • Your core body temperature starts to drop before bed, hits bottom at 3-4 AM, stays constant for about another hour, and then starts to rise when it’s time to wake up

Light and Sleep

  • “We are a dark deprived society in this modern era”
  • Why do you need darkness at night?
    • To facilitate the release of melatonin (a hormone which signals to the body it’s time to sleep)
  • One hour of iPad reading before bed has been shown to blunt the amount of melatonin that’s released by 50%
    • It also delayed the peak of melatonin by 3 hours (melatonin typically peaks a few hours before bed)
    • REM sleep was also decreased
    • There was also a blast radius effect of the iPad reading – negative effects were observed in the following days
  • Hacks:

Yet Another Reason You Can’t Get by on 6 Hours of Sleep

  • REM sleep is dominant in the last half/quarter of your sleep cycle (deep sleep is dominate in the first half)
    • If you typically get 8 hours of sleep and on one night get 6 hours, you lost 25% of your total sleep, but you may have lost 80-90% of your REM sleep

Chronotypes

  • Whether you’re a morning or evening person is genetically determined
    • It’s VERY difficult to change – “When you fight against your chronotype, you’re normally returned by way of disease and illness”
  • Many people don’t have insomnia – they’re just trying to fall asleep at 10 PM when their brain isn’t ready too

We Need to Ditch the Early School Start Times

  • Dave recently pulled his kids out of school to try homeschooling, mainly because schools start WAY too early
    • Kids have late chronotypes – they’re wired to wake up much later than adults
  • “We will look bad with shame and sadness at how we were trying to educate our children amnesic by starting school at 7 or 8 AM”
  • When children start school later (~9AM):
    • Grades increase
    • Behavioral problems decrease
    • Truancy rates decrease
    • Life expectancy increases
      • How? – Road traffic accidents decrease (accidents are the leading cause of death among late adolescence)
        • One study tracked a school which delayed their start time from 7:35 AM to 8:55 AM – they saw a 70% reduction in accidents among students aged 16-18
          • For comparison, anti-lock brake systems resulted in an accident rate drop of ~25% and it was deemed a revolution
  • “If our goal as educators truly is to educate and not risk lives in the process then I fear we are failing our children in a spectacular manner with this incessant mode of early school start times”
  • “When sleep is abundant, minds flourish. When it isn’t, they don’t.”

Enhancing Deep and REM Sleep Using Sound

  • Dave brings up Sonic Sleep, an app designed to do just that
  • Some evidence shows that “pink noise” may improve deep sleep
    • “But the consistency and reliability has been difficult to replicate”
  • “Right now the sound data is unclear”
    • BUT – data has been shown one of the best ways to remove deep sleep is by playing certain auditory tones (done commonly in sleep studies)
  • Think about the ways humans slept on an evolutionary basis – they retreated to silent caves
    • To add – during sleep, the brain shuts off its sensory gate (the thalamus) and inhibits/prevents sound from entering the brain and being processed
    • “All of these things, when I think about it… indicates to me that the invasion of sounds into the brain during sleep is one that evolution tells us isn’t desirable”

Sleep Supplements

  • Bulletproof makes a sleep supplement – Sleep Mode
  • Dave has found Life Cykel’s Lions Mane Liquid Extract increases his REM sleep
    • He takes 7 dropper fulls every night
    • Matt argues – there’s no evidence that shows lion’s mane improves REM sleep”
      • BUT – Absence of evidence is not evidence of absence, so it’s possible

Stop Taking Ambien

  • Using sleep aids (like Ambien) markedly increases your risk of death
    • They’ve also been linked to cancer
    • “Sedation is not sleep, but most people mistake the former with the later when they take them”
  • In 2016, the American College of Physicians stated that sleeping pills very rarely give you much of a benefit beyond a placebo
    • They also advised sleeping pills no longer be the first line of recommendation for insomnia (but rather CBTI instead)
  • Antihistamines (i.e. Benadryl) show similar side effects as the above
    • There’s tons of data linking Benadryl with the inhibition of the ability to move memories from short to long-term 

How long does Matt hope to live?

  • Definitely over 100
    • Matt sleeps EVERY night for 8 hours without question
      • “If you knew all I knew about sleep, you’d choose to do nothing less besides giving yourself 8 hours per night”
      • “I invest in the cheapest, most painless health insurance policy I know of – an 8 hour night of sleep”

Additional Notes

  • Deep sleep has been shown to have a profound effect on blood sugar regulation
  • Comparing a deprivation of food, exercise, and sleep for 24 hours – sleep DECIMATES the others in terms of negative side effects
  • Dave typically gets ~6.5 hours of sleep and aims for ~2 hours of both REM and deep sleep
  • Cognitive behavioral therapy for insomnia (CBTI) has proven to be a remarkably advantageous treatment
    • CBTI improves sleep quality and quantity
    • As an aside, CBTI also decreases paranoia, anxiety, and depression
  • Poor sleep is predictive of a higher number of marital difficulties, marital arguments, and poor marriage quality
  • There is NOTHING within the brain or body that isn’t beneficially improved from sleep
  • During REM sleep, the brain waves go up and down 4-8 times/second (AKA theta activity)
    • During deep sleep, brain waves oscillate 1-2 cycles/second (AKA delta activity)
  • “In the past 20 years, I’ve yet to discover a single psychiatric condition i which sleep is normal”
  • Being lonely increases your mortality risk by 45%
    • Therefore, being lonely is twice as risky for your death concern compared to obesity
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