Dr. Matt Walker: How to Structure Your Sleep, Use Naps & Time Caffeine | Huberman Lab Guest Series

Sleep Structure (00:00:00)

• The episode discusses how to structure sleep for optimal mental and physical health and performance.
• Monophasic sleep schedules involve sleeping in one bout at night, while polyphasic sleep schedules involve sleeping in two or more bouts.
• Napping is also discussed, including how to nap, the ideal nap length, and individual variations in the benefits of napping.
• Sleep and nap needs vary across the lifespan.
• Body position during sleep is crucial for ensuring optimal restorative sleep.
• Napping can improve cognitive performance, especially memory consolidation.
• The ideal nap length is 10-20 minutes to avoid sleep inertia.
• Napping for longer than 30 minutes can disrupt nighttime sleep.
• Napping is not recommended for individuals with insomnia or other sleep disorders.
• Newborns need 14-17 hours of sleep per day.
• Toddlers need 11-14 hours of sleep per day.
• Preschoolers need 10-13 hours of sleep per day.
• School-aged children need 9-11 hours of sleep per day.
• Teenagers need 8-10 hours of sleep per day.
• Adults need 7-9 hours of sleep per day.
• Older adults need 7-8 hours of sleep per day.
• The best body position for sleep is on the back.
• Sleeping on the side is also acceptable, but sleeping on the stomach is not recommended.
• Sleeping on the back reduces pressure on the heart and lungs, improves spinal alignment, and minimizes wrinkles.
• Sleeping on the side can help reduce snoring and sleep apnea.
• Sleeping on the stomach can put pressure on the heart and lungs, strain the back, and cause neck pain.

Sponsors: BetterHelp, LMNT & Waking Up (00:01:29)

• Dr. Huberman emphasizes that the podcast is separate from his teaching and research roles at Stanford.
• The podcast aims to provide free science-related information and tools to the public.
• Sponsors of the podcast include BetterHelp (online therapy), LMNT (electrolyte drink), and Waking Up (meditation app).
• Dr. Huberman welcomes Dr. Matthew Walker to the podcast.

Sleep Phases & Lifespan (00:05:42)

• Sleep can be categorized into different types based on the number of sleep phases within a 24-hour period: monophasic (single sleep period), biphasic (two separate sleep periods), and polyphasic (multiple sleep episodes).
• During infancy, sleep is highly polyphasic due to frequent feeding needs and an undeveloped circadian rhythm.
• As individuals age, the number of sleep phases decreases, transitioning from polyphasic to basic sleep (two sleep periods) by kindergarten age.
• Many kindergarten systems incorporate nap time to support children's sleep needs, and teachers often observe behavioral challenges in children who miss their naps.
• Sleep is crucial for emotional and mental health.
• Children develop monophasic sleep patterns (long sleep at night and wakefulness during the day) around the age of five or six.
• Monophasic sleep patterns continue throughout adulthood and into old age, with some exceptions.

Sleep Stages & Lifespan, Sleep Paralysis & Animals (00:11:58)

• Sleep patterns change throughout a person's lifespan.
• In utero, fetuses experience a sleep-like state similar to REM sleep, characterized by fetal movements during this dream state.
• Infants sleep for extended periods, with a significant portion (50%) spent in REM sleep, which is crucial for brain maturation and social behavior.
• REM sleep impairments are associated with developmental disorders like autism and ADHD.
• During infancy, REM sleep is abundant due to synaptogenesis, but it decreases as non-REM sleep increases from 6 months to 18 months.
• A peak in lighter stage non-REM sleep (stage two non-REM) and sleep spindles is observed during this phase, which is linked to motor skill learning and coordination.
• By age five or six, the ratio of non-REM to REM sleep stabilizes at 4:1, with REM sleep accounting for about 20% of total sleep time.
• Adequate total sleep duration, proper timing, and alignment of chronotype with the 24-hour clock are essential for maintaining this sleep structure.

Adults & Biphasic Sleep, Modern Society (00:20:19)

• In modern society, adults mostly follow a monophasic sleep pattern, but there is some debate about whether this is the natural way for humans to sleep.
• Some cultures, such as hunter-gatherer tribes, still practice a more basic sleep pattern, which includes a longer sleep at night and a short nap during the day.
• Hunter-gatherer tribes also tend to go to sleep about 2 hours after sundown and wake up just before sunrise, which is different from the typical sleep schedule of people in modern society.
• The term "midnight" refers to the middle of the night, but for many people in the modern world, this is the time when they are still awake and active.
• People who have an early sleep schedule, such as those who go to bed around 8:00 PM and wake up around 4:00 AM, may experience midnight as the true middle of the night.
• People with different chronotypes, such as night owls who go to bed later and wake up later, may have a different experience of midnight.
• There is a distribution of sleep schedules among individuals, with some people being more like early birds and others being more like night owls.
• The average sleep schedule of a group of representative humans seems to be centered around midnight, but there are significant individual differences.

Chronotype, Circadian Rhythms & Biological Flexibility (00:25:14)

• Variability in sleep preferences (chronotypes) reduces collective vulnerability by ensuring someone is always awake.
• Circadian rhythm is not exactly 24 hours, allowing for entrainment to the changing light-dark cycle.
• Variations in individual circadian rhythms provide adaptability to different light-dark cycles.
• Variability in chronotypes provides a biological benefit by reducing collective vulnerability.
• Sleep is divided into two types: REM and non-REM sleep.
• REM sleep is associated with dreaming and memory consolidation.
• Non-REM sleep has three stages: N1, N2, and N3 (deep sleep).
• Deep sleep is essential for physical restoration and growth hormone release.
• Napping can improve cognitive performance and alertness.
• The optimal nap duration is 10-20 minutes to avoid sleep inertia.
• Napping too close to bedtime can disrupt nighttime sleep.
• Napping can be beneficial for shift workers and those with sleep deprivation.
• Caffeine is a stimulant that can improve alertness and cognitive performance.
• Caffeine's effects peak 30-60 minutes after consumption.
• Caffeine can disrupt sleep if consumed too close to bedtime.
• The recommended daily caffeine intake is 400 mg (about 4 cups of coffee).

Genetics & Chronotype (00:29:07)

• Chronotype is genetically determined but not necessarily directly inherited from parents.
• People with parents who are both extreme morning types are unlikely to be neutral or evening types, and vice versa.
• Chronotype can be modified by context and exposure to light.
• Constantly being exposed to electric light at night, drinking too much caffeine, and using electronic devices can shift a person's chronotype.

Sponsor: AG1 (00:31:42)

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Biphasic Sleep, Adults; Body Position & Sleepiness (00:32:55)

• Different sleep structures include monophasic, biphasic, and polyphasic sleep.
• Basic sleep for adults involves a long sleep period at night and a short nap during the day.
• An alternative version of basic sleep, known as first sleep and second sleep, involves splitting sleep into two phases across the night, with an awakening period in between.
• There is historical evidence of some cultures practicing first sleep and second sleep, particularly in European cultures during the 15th to 19th centuries, but there is no strong biological evidence to support it as the natural way humans were designed to sleep.
• Body position during sleep, such as incline or decline, can impact sleep features.
• Lying down horizontally facilitates sleep by promoting thermal dissipation, leading to a drop in core body temperature and increased sleepiness.

Naps, Positive Benefits, Nighttime Insomnia (00:40:09)

• Caffeine is a widely used psychoactive stimulant.
• Napping, especially a 90-minute nap during the afternoon, can enhance learning, emotional regulation, and cognitive function.
• Naps help sustain learning capacity, improve emotional regulation, and reset emotional balance by reducing sensitivity to fear and anger while increasing positive perception.
• The benefits of napping are linked to the presence of sleep spindles during sleep.
• Napping releases adenosine, promoting sleepiness, but should be avoided during the day for individuals with insomnia or late in the day to prevent disrupted nighttime sleep.
• The ideal nap duration is between 10 to 30 minutes, with a maximum of 90 minutes to avoid interfering with nighttime sleep.

Tool: Optimal Nap: Duration & Timing; Grogginess (00:49:38)

• The optimal nap duration depends on the desired outcome and individual needs.
• For a quick boost in alertness and concentration, a 20-minute nap is recommended.
• Napping for 20 minutes provides benefits that can last throughout the afternoon and evening, without causing sleep inertia.
• Napping for longer than 20 minutes increases the risk of post-nap grogginess.
• Napping for 5 or 10 minutes provides minimal benefits that quickly fade, while napping for 15 to 17 minutes offers noticeable benefits that sustain longer.
• Avoid napping after 3:00 PM to prevent interference with nighttime sleep.
• Consult a specialist to determine the best nap duration for specific goals and circumstances.

Nap Capacity, “Liminal” States & NSDR (00:58:15)

• Napping can be beneficial for some individuals, but it is not necessary for everyone.
• To improve napping, create a comfortable environment by turning off lights, blocking out noise, and removing your shoes.
• Only nap if you feel the need to during the day, and time your nap based on your natural post-prandial drop, which usually occurs around 1-4 p.m.
• Alternate states of conscious brain activity, such as meditative or liminal states, may provide benefits because they involve local sleep in certain brain regions while still being awake globally.

NASA Nap Culture, Power Naps (01:07:37)

• NASA discovered the benefits of napping in the 1980s to optimize astronauts' performance in space.
• Short naps provided a 20% boost in alertness and almost a 50% boost in task productivity.
• The NASA nap culture influenced the adoption of power naps among non-astronaut employees.

Power Naps (01:07:37)

• Power naps were initially called prophylactic napping but the term was changed to appeal to pilots' alpha male culture.
• The optimal time for a power nap during a long-haul flight is early on, as it sustains alertness throughout the flight.

Sponsor: Eight Sleep (01:11:49)

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• Controlling the temperature of your sleeping environment can help you fall and stay asleep, and wake up feeling refreshed.
• The speaker has been using Eight Sleep for several years and highly recommends it.
• Eight Sleep currently ships to the USA, Canada, the UK, select countries in the EU, and Australia.
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• Dr. Matt Walker is a professor of neuroscience and psychology at the University of California, Berkeley, and the director of the Center for Human Sleep Science.
• He is the author of the book "Why We Sleep: The New Science of Sleep and Dreams".
• In this podcast, Dr. Walker discusses the importance of sleep, how to structure your sleep, the use of naps, and how to time your caffeine intake to optimize sleep.
• Sleep is essential for physical and mental health.
• The circadian rhythm is a 24-hour cycle that regulates sleep-wake patterns, body temperature, and hormone production.
• Disruptions to the circadian rhythm can lead to sleep problems, obesity, diabetes, and other health issues.
• Sleep is essential for:
  • Memory consolidation: Sleep helps to consolidate memories and store them in long-term memory.
  • Emotional regulation: Sleep helps to regulate emotions and prevent mood swings.
  • Physical restoration: Sleep helps to repair tissues, restore energy, and strengthen the immune system.
  • Cognitive function: Sleep helps to improve cognitive function, including attention, concentration, and decision-making.
• Adults should aim for 7-9 hours of sleep per night.
• Children and teenagers need even more sleep.
• It is important to go to bed and wake up at the same time each day, even on weekends.
• Create a relaxing bedtime routine to help you wind down before bed.
• Avoid caffeine and alcohol before bed.
• Make sure your bedroom is dark, quiet, and cool.
• Naps can be a helpful way to catch up on lost sleep or to improve alertness during the day.
• However, naps should be short (20-30 minutes) and taken in the early afternoon.
• Napping too long or too close to bedtime can interfere with nighttime sleep.
• Caffeine can interfere with sleep, so it is important to time your caffeine intake carefully.
• Avoid caffeine in the hours leading up to bed.
• If you are sensitive to caffeine, you may need to avoid it altogether in the afternoon and evening.
• Sleep is essential for physical and mental health.
• By following these tips, you can improve your sleep and overall health.

Tools: Nap Timing, “Fragile” Nighttime Sleep; On-Off-On Protocol (01:12:50)

• Yoga Nidra, also known as yoga sleep, is a practice involving lying down for 30-60 minutes of progressive relaxation to restore mental and physical vigor. A variation of this practice, called Non-sleep deep rest, maintains the critical components of Yoga Nidra but excludes intentions and has shorter 10-20 minute protocols.
• Power napping, developed by NASA and laboratories, is a tool with broader significance. Napping can be beneficial for those who struggle with sleep in the evening, but napping late in the day can make it harder to fall asleep and stay asleep at night. Experimenting with napping earlier in the day, such as after lunch, may improve sleep quality.
• To determine the effectiveness of a sleep intervention, it's important to assess whether symptoms worsen when the intervention is stopped, rather than solely relying on improvements observed during the intervention. This approach involves implementing a negative control (stopping the intervention) and a positive control (resuming the original sleep schedule) to ensure that any observed improvements are not merely placebo effects.

Avoiding Naps: Insomnia, Aging & Sleep Quality Decline (01:18:57)

• Napping is generally discouraged for individuals with insomnia as it can worsen their sleep problems.
• In older adults (over 65 years old), napping may reflect underlying issues with nighttime sleep rather than being inherently harmful.
• During teenage years, deep sleep plays a crucial role in brain development and maturation.
• As we age, our sleep declines, particularly deep sleep, which starts to decline in our mid to late 30s.
• By age 50, we have about 50% of the deep sleep we had at age 17-18, and by age 65-75, it drops to about 5%.
• The decline in deep sleep affects the quality of our sleep, making it more fragmented and less efficient.

Caffeine, “Nappuccino”; Hot Drinks (01:28:20)

• Caffeine blocks adenosine receptors in the brain, preventing sleepiness.
• Napping can reduce accumulated adenosine, aiding nighttime sleep.
• The "nappuccino" combines caffeine and napping to increase alertness, but caution is advised due to potential sleep disruption.
• Caffeine's peak concentration in the bloodstream takes 12-17 minutes, so early perceived benefits are likely due to other factors.
• The smell, taste, and preparation of caffeinated drinks can contribute to alertness through anticipatory arousal.
• Hot caffeinated drinks provide an initial alertness boost from the temperature rise, which prepares the body for waking.
• The caffeine in hot drinks sustains alertness for a longer duration.
• Napping for 25-30 minutes can cause sleep inertia, but a "caffeine nap" of around 20 minutes, timed with caffeine consumption, can provide benefits without negative effects.

Adenosine Clearance, Sleep (01:38:28)

• Besides caffeine and sleep, exercise and cold showers can clear adenosine.
• Many substances, including aspirin, can alter sleep or wakefulness.
• Physical activity increases endorphins and dopamine, which promote wakefulness but don't alter adenosine levels.
• Sleep, particularly non-REM sleep, removes adenosine.
• During deep non-REM sleep, the brain is less metabolically active, producing less adenosine, allowing natural adenosine-clearing mechanisms to work effectively.
• Anesthesia and deep rest states may also reduce adenosine levels by decreasing brain metabolic activity.

Tool: Delaying Caffeine, Afternoon Crash, Sleep Quality (01:43:10)

• Delaying caffeine intake by 90 to 120 minutes after waking can prevent afternoon crashes, improve sleep quality, and provide an accurate assessment of sleep quality.
• Consuming caffeine immediately upon waking blocks adenosine receptors, hindering adenosine clearance and causing increased sleepiness later in the day.
• Caffeine increases brain metabolic activity, leading to more adenosine buildup and earlier sleepiness.
• Abstaining from caffeine for two weeks helps assess true sleep quality and determine the optimal time for caffeine consumption.

Caffeine, Health, Antioxidants; Caffeine Tolerance & Alcohol (01:49:06)

• Caffeine consumption, in moderation, offers health benefits due to its caffeine and antioxidant content.
• Decaffeinated coffee provides similar benefits to regular coffee.
• Caffeine intake should be timed carefully, avoiding consumption within 10-12 hours of bedtime to prevent disruption of deep sleep.
• Sleep trackers may not accurately reflect an individual's sleep quality.
• Overusing caffeine during the day can lead to reliance on alcohol at night, creating a cycle of "uppers and downers."
• Caffeine sensitivity varies among individuals and can be determined through genetic testing or self-assessment.
• For those sensitive to caffeine, it's recommended to avoid caffeine 14-15 hours before sleep and limit intake to one cup.

Tool: Nap “Enhancements”, Caffeine, Light & Face Washing (01:56:54)

• A study compared the effects of different types of naps and other techniques on cognition, mood, and sleepiness.
• All nap groups showed benefits compared to the non-nap group, including improved alertness, cognitive performance, and reduced sleepiness.
• The nap plus caffeine group showed added benefits compared to the nap group, but the benefits were not as substantial as the benefits from the nap itself.
• The nap plus cold hands and face washing group and the nap plus bright light group also showed added benefits compared to the nap group.
• The most effective way to optimize sleep and wakefulness is to wake up, get sunlight, splash cold water on the face or take a cold shower, and delay caffeine consumption.

Polyphasic Sleep, Adverse Effects (02:04:33)

• Polyphasic sleep involves multiple sleep phases within a 24-hour period to increase wakefulness and enhance the benefits of being awake.
• Different polyphasic sleep schedules exist, such as the Uberman, Everyman, and Triphasic schedules.
• The concept of polyphasic sleep dates back to the 1940s with Buckminster Fuller's Daxian principle, which aimed to maximize efficiency by reducing sleep time.
• Claims about the benefits of polyphasic sleep lack substantial scientific evidence and do not improve cognition, productivity, mood, or health.
• Polyphasic sleep schedules decrease the total amount and quality of sleep, reduce REM sleep amounts, and impair cognition, judgment making, decision-making, mood, and metabolic health.
• Polyphasic sleep is not advisable for adults.

Sleep Deprivation & Car Crashes; Polyphasic Sleep (02:12:43)

• Less than 6 hours of sleep increases the risk of car accidents by 30%.
• 5 hours of sleep increases the risk of accidents by 2-3 times.
• 4 hours of sleep increases the risk of accidents by 10 times.
• Polyphasic sleep may increase the risk of car accidents due to reduced sleep duration.
• Monophasic, biphasic, and polyphasic sleep, naps, and caffeine interactions were discussed.
• The importance of sleep at the conceptual, mechanistic, and practical levels was emphasized.
• The upcoming fourth installment of the series on the relationship between sleep, memory, and creativity was mentioned.
• Developmental shifts in sleep across different age groups were highlighted.

Zero-Cost Support, Spotify & Apple Reviews, Sponsors, YouTube Feedback, Momentous, Social Media, Neural Network Newsletter (02:16:49)

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• Dr. Matthew Walker is a leading expert on sleep.
• His book, "Why We Sleep," is a New York Times bestseller.
• Dr. Walker's research has shown that sleep is essential for physical and mental health.
• Sleep deprivation can lead to a variety of health problems, including obesity, diabetes, heart disease, and depression.
• Sleep is also essential for cognitive function, including memory, learning, and decision-making.
• The ideal sleep schedule is one that allows you to wake up feeling refreshed and energized.
• Most adults need around 7-8 hours of sleep per night.
• Children and teenagers need even more sleep.
• It is important to go to bed and wake up at the same time each day, even on weekends.
• Creating a relaxing bedtime routine can help you fall asleep more easily.
• Avoid caffeine and alcohol before bed.
• Make sure your bedroom is dark, quiet, and cool.
• Napping can be a great way to catch up on lost sleep or to improve your energy levels during the day.
• The ideal nap is 10-20 minutes long.
• Napping for longer than 20 minutes can actually make you feel more tired.
• Avoid napping too close to bedtime, as this can make it harder to fall asleep at night.
• Caffeine can be a helpful tool for improving alertness and focus.
• However, caffeine can also interfere with sleep if it is consumed too close to bedtime.
• The best time to consume caffeine is in the morning or early afternoon.
• Avoid consuming caffeine within 6 hours of bedtime.