Sleep is absolutely critical to our health, far more than many realise. Here are a great set of podcasts to help understand sleep in more detail and figure out how to improve sleep:
Dr Matthew Walker on "The Science and Practise of Perfecting Your Sleep"
Dr Andrew Huberman on "Sleep Toolkit: Tools For Optimizing Sleep & Sleep-Wake Timing"
Learning Points
- Definition and Importance of Sleep
- Sleep is likely the single most effective thing you can do to reset your brain and body health.
- It's an incredibly complex physiological process, fundamentally divided into two main types: non-rapid eye movement (non-REM) sleep and rapid eye movement (REM) sleep.
- The Sleep Cycle and its Stages
- Upon falling asleep, you progress through light non-REM stages (1 and 2), then descend into deeper non-REM sleep (stages 3 and 4).
- During deep non-REM, your heart rate significantly drops, and hundreds of thousands of cortical cells fire and go silent together in a unique physiological coordination.
- Sleep occurs in approximately 90-minute cycles for most adults.
- The first half of the night is dominated by deep non-REM sleep (stages 3 and 4).
- The second half of the night sees a shift to more light non-REM sleep (stage 2) and increasingly more REM sleep.
- Specific Functions of Sleep Stages
- Deep Non-REM Sleep: Crucial for natural blood pressure regulation, insulin regulation, and metabolic health.
- REM Sleep: Essential for growth hormone release, peak testosterone levels, various cognitive functions (including learning and memory), and critical for emotional and mental health, described as "overnight therapy". There is an intimate association between emotional/mental health and sleep, with no major psychiatric disorder found where sleep is normal.
- Sleep Paralysis in REM: During REM, the brain completely paralyzes the voluntary muscles of the body (except for extraocular muscles for eye movement and inner ear muscles) to allow for safe dreaming.
- The Criticality of Sleep Quality and Quantity
- Both quantity and quality of sleep are equally important for beneficial next-day outcomes. You cannot be unimpaired with only 4 hours of brilliant quality sleep, nor with 8 hours of very poor quality sleep.
- Occasional brief awakenings, particularly at the end of a 90-minute REM cycle, are perfectly natural, especially with age. However, frequent or prolonged (over 20-25 minutes) awakenings leading to fragmented sleep are detrimental.
- Environmental Factors and Sleep
- Light Exposure: Exposure to bright light (ideally sunlight) early in the day helps convey the time of day to the brain and body and supports wakefulness. Conversely, reducing light later in the day helps prepare for sleep. Studies showed workers exposed to natural daylight had significantly increased sleep time (over 30 minutes) and sleep efficiency (5-10%).
- Temperature: Your 24-hour circadian cycle is influenced by temperature changes; light exposure should align with rising temperatures in the morning and decreasing temperatures in the evening.
- Impact of Substances on Sleep
- Caffeine: Has a half-life of 5-6 hours and a quarter-life of 10-12 hours. It blocks adenosine, masking natural tiredness. When caffeine wears off, you experience a "tsunami wave" of accumulated adenosine, leading to a crash. Even if you fall asleep, caffeine can reduce the depth of your deep sleep by up to 30%, which is equivalent to aging yourself by 10-12 years. This can lead to a dependency cycle where you need more caffeine to wake up.
- Alcohol: Classified as a sedative, not a sleep aid. It causes you to lose consciousness quicker but doesn't induce naturalistic sleep. Alcohol fragments sleep (causing many conscious and unconscious awakenings) and is potent at blocking REM sleep. The brain then tries to "rebound" by increasing REM sleep later, leading to intense, bizarre dreams, but it never fully recovers the lost REM.
- Marijuana (THC): Can speed up the time it takes to fall asleep, but the brainwave signature is not ideal, making it "non-natural". Like alcohol, THC blocks REM sleep, leading to a REM sleep debt and intense dreams when usage stops.
- Melatonin and its Role
- Melatonin is a hormone produced by the pineal gland that signals to the brain and body whether it's day or night, and thus when to think about sleep.
- It acts as a "starting official" for sleep, calling the brain and body to the line, but does not participate in the race itself; it doesn't help with the generation or overall structure of sleep.
- For healthy adults who are not older, melatonin supplementation is generally not particularly helpful as a sleep aid, only increasing total sleep by an average of 3.9 minutes and sleep efficiency by 2.2%.
- Typical over-the-counter doses (1-20mg) are supra-physiological, often 10 to 20 times higher than what the body naturally produces. Optimal doses, where benefits are seen in specific populations, are between 0.1 and 0.3mg.
- Older adults (60-65+), especially those with insomnia, are the main population who may benefit from melatonin, due to age-related calcification of the pineal gland affecting natural melatonin release.
- Naps: Benefits and Risks
- Naps can offer significant benefits for cardiovascular health, blood pressure, cortisol levels, learning, memory, and emotional regulation. NASA studies in the 1990s showed 26-minute naps improved mission performance by 34% and daytime alertness by 50%.
- However, naps also have a "dark side": they reduce sleep pressure. For people who struggle with sleep at night (insomnia), napping during the day can make their nocturnal sleep problems even worse.
- Societal Stigma Around Sleep
- Society has often stigmatized sleep as "slothful" or "lazy," leading people to feel embarrassed about needing sleep or taking naps. It should be viewed as a fundamental human and civil right.
- Approach to Sleep Improvement
- A hierarchical approach is recommended: behavioral tools first, then nutrition, then supplementation, then prescription drugs.
- Prescription sleep aids are short-term solutions for some forms of insomnia but are not recommended long-term, as they can lead to rebound insomnia.
- Cognitive Behavioral Therapy for Insomnia (CBT-I) is a non-drug, psychological approach that is as effective as sleeping pills, and even more effective in the long term, with benefits lasting almost a decade.
Action Points
- Optimise Light Exposure
- Aim for at least 30 to 40 minutes of natural daylight exposure early in the day. This helps set your circadian rhythm.
- Reduce light exposure in your eyes later in the day and in the evening.
- Manage Caffeine Intake
- Halt caffeine intake 8 to 10 hours before your typical bedtime. This helps prevent caffeine from disrupting the depth of your deep sleep.
- Avoid Alcohol and THC for Sleep
- Recognise that alcohol and THC cause sedation, not natural sleep. Avoid using them as "nightcaps" or sleep aids, as they fragment sleep and block crucial REM sleep.
- Use Naps Wisely
- If you do not struggle with sleep at night, naps are beneficial.
- To avoid grogginess upon waking, limit naps to about 20-25 minutes, which prevents you from descending into the deepest stages of sleep.
- If you choose to have a longer nap (e.g., 90 minutes for a full sleep cycle), be aware it might impact night sleep.
- Avoid napping late in the afternoon (e.g., 6-7 hours before your usual bedtime).
- If you have insomnia, typically avoid napping altogether, as it can worsen nighttime sleep problems.
- Prioritise and Protect Your Sleep
- No one should feel guilty or unproud about getting the sleep they need; it's a fundamental human right.
- Implement "Unconventional" Sleep Tips for a Bad Night
- "Do Nothing" Strategy: If you have a bad night's sleep, do not sleep in later, do not nap, do not consume extra caffeine, and do not go to bed earlier. Maintain your normal wake-up and bedtime to rebuild sleep pressure and prevent further disruption.
- Establish a Wind-Down Routine: Treat sleep like "landing a plane" by gradually descending. Engage in a routine 1-2 hours before bed that includes activities like light stretching, meditation, or reading. Avoid watching television in bed due to light exposure and activating content.
- Use a "Worry Journal": One or two hours before bed, write down all your concerns. This acts like "closing emotional tabs" in your brain, helping to clear your mind and reduce the time it takes to fall asleep by as much as 50%.
- Remove Clocks from the Bedroom: Eliminate all visible clock faces, including your phone, from your bedroom. Knowing the time during nighttime awakenings can increase anxiety and worsen the situation.
- Consider CBT-I for Insomnia
- If struggling with long-term insomnia, explore Cognitive Behavioral Therapy for Insomnia (CBT-I) as a highly effective, non-drug-based approach.