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The basics of how sleep works and how to work on your sleep
For body nerds like me sleep is absolutely fascinating.
Sleep is a “drive” - like hunger, thirst, or sex. These are physiological, hard wired human needs that are controlled by the hypothalamus, a very old part of the mammalian brain. The cool part about sleep? You can’t psych yourself out of being thirsty; but you can 100% get yourself so worked up about sleeping that you’ll struggle to do it.
The other thing about sleep?
It’s 100% essential for a well functioning system.
In the short term, forgoing sleep can make you less productive or moody.
In the long term, compromised sleep can seriously mess with your physical and mental health, longevity, wellbeing, and success.
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Why Do We Need Sleep?
Sleep does 2 primary things for a human organism: cleans the brain and repairs damage done to the structures of the body. You may have heard that a good workout is about controlled damage to human tissue, and that gains are actually made in recovery. The “recovery” primarily happens during sleep. So what’s going on?
Cleaning the Brain
Did you know that while you sleep your brain shrinks and swells (so cool!)? It’s true. Sleep happens in 90 minute micro-cycles. During that time the brain shrinks just a tiny bit and fluid from near the spinal column floods in, just like a tide washing up. That “tide” is collecting adenosine, the chemical waste product of every synapse that fires in your brain. If adenosne builds up it damages the brain - which is one theory of why poor sleep has been liked to degenerative diseases like Alzheimers and Parkinsons.
Repairing the Body
When we sleep many of the maintenance and restorative functions of the body do their work. We all know the feeling of getting over an illness, sleeping 11 hours, and waking up feeling like we’ve been reborn. Those same processes are happening during your nightly rest.
That’s also when memories are stores and the central nervous system consolidates learning. Every struggled with a task or idea, you sleep on it, and it’s better in the morning? Yup, that’s sleep doing it’s job.
For those of you interested in athletic performance or improving health, sleep plays an important role in your Gainz (TM). When you lift you’re doing intentional damage to muscle and connective tissue, and when you sleep you’re repairing that damage to be stronger than your initial efforts. Without adequate and high quality sleep you don’t really get the full benefit of that gym time, and may even lead to increase injury risk long term.
How Sleep Works
Sleep is governed by two primary mechanisms: circadian clock and sleep drive.
There was a recent full post on circadian rhythm:
So let’s look at sleep drive.
Sleep drive is the gradual accumulation of adenosine in the brain. Ever had a really mentally challenging day and are exhausted even though you didn’t “do” much with your body? The adenosine from all that deep thinking has built up in your brain and it needs a wash.
This is why there is no chemical replacement for sleep!
There is no other way to satisfy sleep drive than sleeping. Too much adenosine in the brain damages it - and if you go long enough without sleep you’ll lose touch with reality and even die.
Stages of Sleep
General consensus and most wearables (like FitBit, Oura, or WHOOP) use three stages of sleep: light, deep, and REM. Light is that dozy snooze when you first get to sleep. Deep is the restorative phase when you’re repairing. REM stands for Rapid Eye Movement and is when you’re dreaming, working out your problems, and consolidating memories.
You move through sleep phases in 90 minute cycles, with more deep sleep early in the night and gradually more REM sleep.
When you get to bed late, drink alcohol, use THC, or are on screens just before bed you can lessen the access to deep phase sleep. Here’s the night above compared with a night where I had 2 alcoholic drinks, got to bed an hour late, and had been overstimulated from bright lights:
I got about 20% less deep phase sleep because the first 2 - 90 minute cycles were disrupted as my body processed the alcohol.
Getting Better Sleep
Part of the keys of getting better sleep lie in imagining how our evolutionary ancestors would’ve slept. After the sun went down in the absence of artificial light the brightest thing would’ve been a camp fire or the full moon. You would’ve been surrounded by your community, at a lower temperature than the day time, probably eating as the sun was going down (if you’ve never cooked in the dark over a camp fire: it’s difficult, messy, and inefficient).
In the lull of that twilight or darkness your cortisol, the hormone of stimulation, would’ve been very low. In it’s place your melatonin, a hormone you naturally produce, would increase and peak as you’re falling asleep.
If there was a threat - like a loud noise, someone yelling, the fear of a predator, or something else that would stimulate your adrenaline - you’d snap to attention. Think about all of your senses. Any of them could be stimulated and your adrenal hormones would block both your melatonin and your sleep drive.
Why does that all matter?
Bright screens, loud noise, arguments with our partners, anxiety about the news, murder podcasts - all of those can stimulate your system and block your natural melatonin and sleep drives. Ever felt “tired but wired”? That’s this overstimulation happening.
(Remember: melatonin is part of your circadian cycle and sleep drive is adenosine accumulating in your brain.)
Back before 2020 I worked in New York City in a fancy luxury gym. From 5:30a to 11p they were all bright lights and loud music. I’d be up at 5, on the subway by 5:45a with music blaring in my ears. 45 minutes to work, sessions all day, getting home at 7p or 8p, quick dinner less than an hour before I intended to sleep.
No wonder my sleep was garbage. My nervous system was on overdrive.
So much for being a “fitness professional”.
Getting better sleep doesn’t start with a wearable widget (though they can help, yes) or a fancy pillow (yes, that might help, too). It isn’t about melatonin supplementation.
The quality of your sleep is dictated by your behavior the day before.
The amount of sun exposure you get, your relationship and timing of caffeine, and the ways you stimulate your body and mind after the sun goes down. There are a few key things that you can shift in your sleep environment, but the most important differences happen in your lifestyle.
1. Consistent Waking Time & then Bright Light
If you haven’t read the circadian rhythm article you’ll want to do that to understand this one. Simple version: wake up around the same time every day and get bright light in your eyes ASAP. If natural sunlight is available that’s preferred.
2. Your Environment
Your sleep environment (probably your bedroom) should be cold, a consistent volume, cozy, and really dark. Blackout curtains and light air movement are a good idea. TVs are really not - and studies show couples with TVs in the bedroom have less intimacy.
3. Better Living Through Chemistry
Caffeine is an adenosine blocker and your sensitivity to caffeine is governed by genetics and shows up in the liver. Specifically, how quickly your liver enzymes can process caffeine and get rid of it. If you’re a slow caffeine metabolizer, a second cup of coffee makes you feel jittery. If you’re a fast caffeine metabolizer you can drink the whole pot and feel fine. Either way: cut caffeine mid day.
4. Set Up Your Wind Down
You are the expert on your life, so you’re the one who knows what’s going to work for you. But chances are you’ve had days you overstimulate yourself too close to bed and end up waking a bunch. Bright lights, loud noises, alcohol, sugar spikes and crashes - none of these are helping you get and stay asleep. Consider how you might help relax your nervous system more completely before trying to fall asleep.
Quick word on melatonin
Melatonin is a hormone your body naturally produces. It’s also a supplement some people take to “induce sleep”. If you’re consistently in the same time zone and generally on the same schedule this is pretty unnecessary (if you think it is necessary, you probably want to have a sleep study done).
When is melatonin useful? When switching time zones, changing work schedules, or resetting circadian cycles. During those times you want to get calm (remove overstimulation), give yourself 15 - 30 minutes for it to take affect, and then “ride the wave” of the drowsiness that will come over you. If you take it and watch a horror movie it’s not going to work because the adrenal stimulation will over-ride the melatonin.