Episode 31: Dr. Matthew Walker: The Science & Practice Of Perfecting Your Sleep| Huberman Lab

Key Takeaways

  • “Sleep is probably the single most effective thing you can do to reset your body and health” – Dr. Matthew Walker
  • Sleep is so significant in our health, you really can’t sacrifice non-REM deep sleep or REM sleep without damage
  • “There is no major psychiatric disorder we can find in which sleep is normal.” – Dr. Matthew Walker
  • REM sleep is the most predictive of longevity and lifespan
  • Any amount of alcohol and THC will disrupt REM sleep
  • If you can nap without disruption to your sleep at night – go for it! Otherwise, stay away from naps
  • Pro-sleep behaviors: sleep and wake up at regular times, keep the temperature cool, keep the room dark, limit caffeine intake window, do your best to minimize or eliminate alcohol, have a wind-down routine
  • Priority of events to improve sleep: behavioral tools (light viewing behavior, caffeine, and alcohol, etc.) – nutrition – supplementation – prescription drugs – brain-machine interface
  • Unconventional tips for better sleep:
    • Don’t alter your sleep schedule if you have a bad night of sleep
    • Have a wind-down routine
    • Write down your worries from the day 1-2 hours before sleep
    • Remove all clocks from your room and don’t check the time on your phone

Introduction

Matthew Walker, Ph.D. (@sleepdiplomat) is a sleep expert and 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 and host of his own podcast, The Matt Walker Podcast.

In this episode of Huberman Lab, Drs. Huberman and Walker discuss the biology of sleep, including its various stages and what specifically happens to those stages when we don’t get enough sleep. They also discuss the effects of sunlight, caffeine, alcohol, naps, hormones, exercise, marijuana, sexual activity, and various supplements on sleep.

Host: Andrew Huberman (@hubermanlab)

Book: Why We Sleep by Matthew Walker, PhD

Sleep Cycles And Nuances Of REM Sleep

  • Sleep is the most fundamental layer of physical and mental health
  • “Sleep is probably the single most effective thing you can do to reset your body and health” – Dr. Matthew Walker
  • Sleep as a process is complex in terms of physiology
  • Our assumption has been that we evolved to sleep but it’s possible that from sleep, wakefulness emerged
  • Sleep is separated into two main types: (1) rapid eye movement (REM) sleep and (2) non-REM deep sleep
  • Sleep cycles: non-REM and REM play for brain domination throughout the night in 90-minute cycles
  • The ratio of non-REM and REM throughout the night: the first half of the night is dominated by non-REM deep sleep; the second half of our sleep is dominated by REM sleep
  • If you sleep hours later than usual (maybe because of an event) – you will likely have more REM sleep cycles and less deep sleep
  • REM sleep is often called “paradoxical sleep” because the brain is highly active in this stage
  • We also see serotonin and norepinephrine shut off during REM sleep, and acetylcholine ramp up
  • In REM sleep the brain paralyzes the body so the mind can dream safely without body taking action
  • Just before entering REM sleep, the brainstem sends a signal down the spinal cord and locks the voluntary muscles of the body in paralysis
  • Only two voluntary muscle groups are not paralyzed: (1) extraocular muscles and (2) inner ear muscle – though the reason these two are spared is unknown
  • REM sleep is nature’s emotional regulation and therapy
  • Studies have shown an inverse relationship between REM sleep and all-cause mortality: the lower your REM sleep, the higher all-cause mortality

Non-REM Deep Sleep & Stages Of Sleep

  • There is really no state in wakefulness that is like true slow waves of non-REM deep sleep
  • Deep sleep allows you to save memories in the brain
  • Non-REM deep sleep is divided into four stages, increasing in the depth of sleep: stages 1 and 2 are light stages of non-REM deep sleep; stages 3 and 4 are deep stages of non-REM deep sleep
  • In stages 1 and 2: heart rate begins to drop, brain wave activity slows down
  • In stages 3 and 4: heart rate is low, cells in cortex fire together then go silent

Hormone Regulation During Sleep Cycles

  • Sleep should be evolutionarily selected against as during sleep we are vulnerable to predation which one could imagine would have made sleep selected out – but it hasn’t so it must serve a significant function
  • Hormone regulation and dysfunction are different during non-REM deep sleep and REM sleep
  • During non-REM deep sleep, we get autonomic restoration and regulation of heart rate and blood pressure
  • Insulin regulation of metabolism is disrupted in cases where non-REM deep sleep is insufficient
  • Growth hormone and testosterone are tied to REM sleep

Sleeping The Whole Night Through Versus Involuntary Disruptions To Sleep

  • Sometimes you will wake up in the middle of the night for some reason – maybe to use the restroom, maybe you just wake up
  • It’s natural to wake up in the middle of the night, especially with age
  • When we finish 90-minute cycles, almost everyone wakes up and changes position because the body has been paralyzed in REM
  • Healthy sleep efficiency: of the total amount of time in bed, we want to be asleep approximately 85% or more asleep
  • Intervene in fragmented sleep if you are waking up 6-7 times per night, or if wakeful periods are 20-25 minutes
  • Uberman schedule: person sleeps in 90-minute bouts throughout day and night
    • If you sleep in accordance with the natural sleep cycles mother nature gave us, your health will be better

Light Exposure

  • Stack cues for wakefulness early in the day
  • In the first half of the day, get at least 30-40 minutes of direct sunlight each morning to feel more alert – can do this even by working next to a window with natural light coming through
  •  Sleep time and efficiency can increase dramatically if you are working in an area with a window
  • If you can do it safely, minimize the time in sunglasses to accurately convey information about time and day to the rest of the body

Caffeine

  • It’s best to allow natural signals to wake up the body by delaying caffeine intake 90 minutes after rising
  • How does caffeine work to wake us up: caffeine is a psychoactive stimulant that increases dopamine and blocks adenosine (which makes us sleepier)
  • Caffeine crash: when coming down from caffeine, you lose the effects of caffeine, and the level of adenosine you suppressed comes rushing in
  • The dose and timing of coffee is what makes it helpful or harmful
  • The half-life of coffee is 5-6 hours depending on liver enzyme
  • Even if you don’t feel the effects of late caffeine intake on sleep, cycles will likely be disrupted – particularly deep sleep
  • You might fall asleep and stay asleep well, but increase caffeine intake the next day because you don’t feel rested
  • Suggestion for last caffeine intake: 8-10 hours from the time you would like to sleep

Alcohol

  • Alcohol is a sedative but not a sleep-aid
  • People tend to turn to a “nightcap” or evening drink to help them fall asleep and turn off thoughts and planning
  • Negative impacts of alcohol on sleep:
    • You lose consciousness quicker but are not achieving quality sleep
    • Alcohol fragments sleep so you will wake up many times throughout and will not have continuous sleep
    • Alcohol is a potent REM sleep blocker  
  • Even one single glass of wine with dinner will reduce REM sleep time and can even cause declines in growth hormone release over time
  • Timing (e.g., day drinking) and dose make a difference with alcohol but specifics are unknown

Marijuana And CBD

  • Marijuana disrupts sleep
  • Marijuana consists of THC and CBD (non-psychoactive components)
  • Like alcohol, THC blocks REM sleep – when you stop marijuana/THC, REM sleep will resume and even try to regain lost REM sleep
  • Another concern about using THC for sleep is withdrawal dependency which induces significant rebound insomnia
  • CBD levels are often misreported on label
  • In some studies, CBD promotes wakefulness
  • It doesn’t seem that CBD is as disruptive as THC – but there isn’t enough information about CBD to make informed suggestions
  • Possible avenues CBD may enhance sleep – if at all: (1) thermoregulation, (2) anxiety reduction, (3) may modulate adenosine sensitivity

Melatonin In Naturally Occurring Form Versus Supplement

  • Melatonin starts to rise in as dusk approaches, peaking around the time of sleep itself
  • Melatonin tells the body when it’s day and night and can help with the timing of sleep but not induce sleep
    • Analogy: melatonin is like a race director who calls all racers to the line but doesn’t participate in the race itself
  • Darkness triggers the release of melatonin: (1) try dimming lights in the house in the evening; (2) avoid blue light
  • Melatonin is not particularly helpful as a sleep aid – a recent meta-analysis showed melatonin only increased sleep by about 4 minutes and sleep efficiency by about 2%
  • Potential positive effects of melatonin for some people: may drop core body temperature, potential antioxidant effects, older adults who have a lower reduction of natural melatonin release, may reduce anxiety – or – placebo!
  • Problems with melatonin dosing: the amount of melatonin in supplements is orders of magnitude greater than amounts of melatonin naturally released in the system
  • There is evidence that melatonin suppress puberty and should be used with caution as a sleep supplement

Sleep Supplements

  • There are many forms of magnesium but the two helpful for sleep are: magnesium biglycinate and magnesium threonate
  • Huberman’s sleep cocktail:mangesium threonate at 200-400mg 2-3 hours before sleep; theanine 200-400mg; apigenin 50mg – leave out the theanine if you sleepwalk
  • We don’t have good studies that have specifically talked about magnesium threonate – and the literature for magnesium for sleep, in general, does not provide compelling evidence
  • If you have healthy levels of magnesium, it’s unlikely you need to supplement
  • Magnesium has shown benefits in older adults with insomnia
  • Valerian root: evidence does not support the use of valerian root for sleep
  • Tart cherries: sound studies have shown that consuming tart cherry juice can reduce time awake throughout the night and increase minutes of sleep
  • Kiwi fruit: eating kiwi with skin on seems to decrease the speed of time to fall asleep and increase sleep duration – maybe mediated by the GABA system
  • Tips for self-experimentation:
    • Gauge where you currently are for about one month
    • Take a supplement of interest for about one month
    • Do the negative experiment – come off the supplement for one month and see if things get worse – if it’s worse, it might be worth taking

Nap

  • There is a lot of individual variation in tolerance for naps
  • Naps are a double-edged sword: if you struggle with sleep at night, do not nap during the day in order to build up sleepiness and hopefully sleep at night
  • If you have fragile sleep and insomnia – don’t nap during the day because you’re releasing healthy sleep pressure that’s built up
  • If you nap regularly and sleep well at night, go for it!
  • Naps as short as 17 minutes can have great benefits on learning on memory
  • Tips for a good nap: keep it brief (20-25 minutes), keep it 7-8 hours before you want to sleep

Can You Sleep Too Much?

  • Depression can come from anhedonia, so you stay in bed longer but are not necessarily sleeping more
  • Sleep is not a linear relationship: it is true that the shorter your sleep, the shorter your life – however – past 9 hours of sleep the mortality curve rises again
    • BUT, being in bed too long may be compensation for fragmented sleep
  • Sleep quality and poor sleep efficiency is a predictor of mortality
  • When we are sick, we want to sleep more
  • Sleep doesn’t seem different than other things in our life – you can overeat, you can over-exercise, you can over-hydrate, etc. – it seems logical you can get too much sleep

Effects Of Sex, Orgasm, & Masturbation On Sleep

  • Post-orgasmic increase in prolactin is thought to be a natural sedative
  • Sex that results in orgasm (for both people involved) seems to improve pair bonding and can promote pro-sleep hormones
  • People will self-report using masturbation as a sleep aid
  • Sleep can also help with relationships and sex: estrogen and testosterone are under profound regulation under sleep – too little sleep and sex hormones are significantly disrupted
  • Restless nights of sleep trigger more fights and predict higher rates of conflict and less resolution because empathy decreases with sleep
  • For every 1 hour of extra sleep, a woman gets, her interest in sexual intimacy increases by 14%

Unconventional Sleep Considerations & “What Ifs”

  • If you have a bad night of sleep, do nothing: don’t wake up later, don’t sleep earlier, don’t nap, don’t increase extra caffeine
  • Have a wind-down routine: it takes time to gradually unwind and fall into a restful sleep – we do this with kids but stop as we get older
  • Don’t count sheep! But do take yourself on a mental walk and visualize nature to get your mind off itself
  • An hour or two before bed: write down the things that are bothering you, so you unload your concerns
    • Difficulty and anxiety in sleep are not the same as they are during the day – we tend to ruminate and catastrophize disproportionately during sleep
  • Remove all clocks from your bedroom and resist checking the time on your phone
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Notes By Maryann

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