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How Sleep Is Supposed to Work

Updated: Feb 13


From the old to the young, richest to poorest, human and animal alike, who doesn’t love a good night’s sleep? Dozing, snoozing, napping conking out, getting some shut eye—no matter what you call it there’s nothing quite like it. Yet despite this love for sleep I think you’d agree that we don’t do a particularly great job with it in America. Whether it’s because we aren’t allowing enough time for sleep or we’re doing things that disrupt quality of sleep (possibly both), this uber-important part of our day has has been devalued in the hustle of the modern world. Sleep statistics over the last decade all back this up.

Sleep can be your hidden superpower if you use it your advantage. It can make you look younger, feel better, think more clearly, improve performance and body composition. Sharper cognitive function, better memory recall, more energy and vigor, healthier joints, stronger muscles, better immune function—they’re all right there for the taking if you give your body the sleep it needs. Forget the daily sudoku or Omega 3’s food, sleep is five times more beneficial for your cerebral matter than brain training or brain food. And you can ditch the Epsom salts. If you want to avoid muscle soreness aim to fall asleep by 10:00pm at the latest every night.

Sleep can also be your worst enemy if you don’t get enough of it. We’ve all experienced the brain fog bad after a night of poor sleep. That “fog” is the toxins that accumulate in your brain and cloud your cognitive pathways—toxins that normally get cleared out during R.E.M. sleep—making it difficult to think straight or to maintain any kind of focus. Deep sleep (different than REM) is when your muscles, connective tissue and joints get repaired; if you’re always sore or achy you may need to look no further than your pillow to remedy this.

The problem, generally speaking, is twofold as I see it:

1. We’re simply not sleeping enough. This is something of a “duh” statement but it still needs to be said. We’re going to bed too late, getting up too early, or some combination of the two. The American day been stretched too thin at the cost of fewer sleep hours. We even view it as a positive to skip out on sack time (the “I’ll sleep when I’m dead” mentality).

2. We’re sabotaging sleep quality. This one isn’t a straightforward equation like hours in bed and it can be a little trickier to solve. As modern humans we have a lot of habits that disrupt our circadian rhythms, confuse our brain about what time of day it actually is, and disrupt the deep sleep we really need as human beings.

Too much screen time at night, not enough time in the regulating power of the sun, too many stimulants, too much stress revving up the nervous system and telling our brain to keep us wide awake. All bad things for sleep. Things get especially bad at night where we spend the last hours of our day on devices, losing ourselves in the magnetic pull of the social media feed, gaming, binging on Netflix… often until the last few seconds before we close our eyes. None of this lines up with our biology and we’re paying price for it by losing out on deep restorative sleep.



Fixing sleep patterns isn’t like taking your car into the shop. These are habits you personally have to work on and unfortunately there aren’t any true shortcuts here. To understand what’s potentially going wrong with sleep I think we need to back up and look at how it all works in the first place. But the good news here is that sleep science is actually pretty straightforward—like a lot of human biology—and when we get down to the inner workings it’s pretty obvious what we need to do to align things. At its core it all centers around two things: the circadian rhythms in your brain and the hormones that control sleep—melatonin and cortisol. In combination these factors account for 90% of your sleep function. Anyone who sleeps well would find these humming along the way they’re supposed to, and anyone who sleeps poorly would find some kind of disruption here.

As you can see in the highly indicative graph above, cortisol and melatonin are on opposite daily cycles and it’s all synchronized with sunrise and sunset. That’s because these hormones serve completely opposite biological functions—cortisol revs your system up and melatonin calms it down, so it logically follows that one gets produced in the morning and the other in the evening. Cortisol starts to kick in around 6:00am (it’s your natural alarm clock), tops out around 10:00am and then steadily declines until 10:00pm. Melatonin is on the reverse trend, hitting its lowest point at 6:00am and peaking at 10:00pm-ish (it’s your natural sedative). This shifts around a bit throughout the year as the days get longer and shorter but these hormones always follow the cycle of light and dark. It’s what they’re built for.

It’s a perfectly balanced and self-regulating system when it’s working the way it’s supposed to. Cortisol gets released to boot your system up in the morning, gets your mental faculties going by enhancing the effects of certain neurotransmitters, and generally helps you become a fully alert and active human being. Melatonin reverses this process at the end of the day, down-regulating your nervous system, slowing your heart rate down, and switching your brain waves into sleep mode. Each day is a repeat of the one before, circadian rhythms run smoothly and repetitively, you get proper sleep and everything stays in tip top shape. But of course it doesn’t always work that way.

Too often our brain gets shuffled around because we do things that don’t line up with this natural daily cycle. We rev cortisol up at the wrong times—with external stimuli like caffeine, blue light exposure or even intense exercise, or internal stimuli like anxiety—which then prevents us from switching into sleep mode when we need to. Or conversely if we don’t get enough sunlight earlier in the day cortisol production doesn’t peak the way it’s supposed to, which can also throw off circadian function and ultimately lead to poor sleep. If functioning in the morning without caffeine is almost impossible for you it’s likely not just because you’re “tired”, it could be a sign your cortisol pathway is off in some way. Coffee can be a great complement to natural cortisol production in the morning (and who doesn’t love that first cup?) but you shouldn’t feel like you need it everyday.

Melatonin has its own set of parameters (and potential problems). Because it’s triggered by darkness, if your environment is too bright at night— especially if it’s overhead lighting—your body won’t produce enough of this hormone when you need it. To your primitive wiring when light comes from overhead it means the sun is still up, and why would your brain release a sleep hormone at 3:00pm? Blue-light emitting devices aggravate the problem, because this is the type of light present until bedtime and you’ve got a recipe for insufficient melatonin production. Not surprisingly Americans are turning more and more to artificial sleep remedies. We take twice as much supplemental melatonin as we did a decade ago and this trend appears to be increasing with each passing year.



Your brain needs data to make decisions, and all day long it is receiving feedback from the environment that literally tell it what time it is. This info goes directly to your body’s internal clock embedded in your hypothalamus, the region of your brain that houses all your basic impulses. Appetite, emotion, sexual impulses, hunger and thirst… we’re dealing with some guttural stuff here and it all gets mixed up together with sleep. Being in the wrong emotional state (nighttime anxiety anyone?), being in the wrong physiological state (elevated heart rate and blood pressure), eating the wrong foods at the wrong times—all of these are potential detriments to sleep. And this brain activity happens within an inch or two of your internal clock.

So how does your brain set this internal clock of yours? There’s quite a list of stimuli your brain uses (some of which might surprise you); while they have varying degrees of manageability they are all under your control to some extent.


When it gets down to it light is the biggest time cue of them all. This shouldn’t be super surprising since the day is defined by light and dark and all your circadian rhythms are built around this. But you need to appreciate the full power light has over your sleep quality, in no small part because it’s the time cue we’re screwing up the most in the modern world. Your internal clock is actually plugged directly into your eyes so the feedback it gets from them is hugely important to your circadian function and sleep patterns. If you ignored every other part of the sleep mechanism and only focused on light exposure your sleep would automatically improve.

At its core your brain has fairly primitive wiring that evolved when there were only three kinds of light: sunlight, moonlight, and firelight. Even in 2023 this is still what the human eye prefers to see. And the natural light spectrum looks very different at dawn, midday, and dusk, as well as the direction light comes from. Picture what conditions would look like at 8:00-9:00pm in the primitive world: trace amounts of sunlight (if any) coming from the orange end of the spectrum and sitting at horizon level, faint amounts of moonlight coming from above, and maybe a fire or torch throwing off more orange light from the ground. That’s what our nighttime space should look like.

If you’re like the average American though, your evenings might not look anything like this. Artificial and/or bright lighting, blue light devices into the late hours of the night, overhead illumination--this is the typical home environment at night, and all three of these go in direct opposition to the primitive wiring in the human brain. To make things worse we aren’t getting enough natural blue light earlier in the day, or sunlight in general for that matter, so our brain isn’t getting the stimuli it needs to properly set its clock from the outset. It's no wonder if your brain feels like a scrambled mess at night... it very likely is.



Caffeine and alcohol are very different animals—one is a stimulant and the other is a depressant—but the big thing they have in common is they both alter your natural physiological state and anything that does that has the potential to impact your sleep patterns. Of the two caffeine might be a little more obvious; that same boost it gives you in the morning can easily translate to being stuck wide awake at night. But did you know that alcohol has been shown to significantly reduce REM sleep? Let’s take a look at how they each affect circadian function and the setting of your body clock.

Caffeine works in a fairly direct way on your body clock. It triggers the release of neurotransmitters and hormones that rev up your nervous system and put you in a more alert state, which is like telling your brain that it’s still 10 o’clock in the morning no matter the actual clock says. So if this is happening in the middle of the evening it’s likely not going to be conducive to great sleep at night. And be careful with caffeine—it has a half life of up to ten hours. That means that a small cup of coffee at 12:00pm can leave some caffeine lingering around in your system as late as 10:00pm. Even it’s not a massive amount it can be enough to disrupt sleep in those precious first few hours when physical repair takes place. So try to make coffee a morning thing!

Alcohol is a little bit sneakier in the way it affects sleep. Obviously it has the power to knock us out (and quickly) but what happens on the back end you might not expect. Alcohol inhibits your system—partly what we love about it—but this eventually creates a reverse effect. Your body’s homeostatic drive kicks in, lowering your body’s innate production of inhibitory neurotransmitters which can cause low-level systemic stress or acute anxiety… even full blown panic in some cases. So even if you're actually asleep alcohol might prevent you from getting the coveted R.E.M. sleep that’s so important for cognitive health and function. The bottom line here is that the occasional glass of wine isn’t going to wreck things for you, but habitual alcohol intake can and will cause big problems for sleep quality.



Regular physical activity has awesome effects on sleep and sleep quality. Generally speaking exercise = great sleep. But (isn't there always a but?) if you’re doing it in the wrong way at the wrong times--specifically on a schedule that doesn't line up with your natural hormone levels--it can negatively affect your sleep quality. Take an intense Crossfit session for example. This kind of workout puts your body into “fight” mode and revs up the nervous system, which is generally an awesome thing. But doing this at times when cortisol levels are supposed to be low—like very early or late in the day (think 5:00am or 8:00pm)—gives your brain the wrong time cues and can disrupt that finely tuned balance between cortisol and melatonin.

On the flip side of this low intensity exercise in the evening, like walking or yoga, is a great idea. Activities like these lower your cortisol levels, put your nervous system into "rest and digest” mode and help to synchronize your hormones in a way that’s conducive to sleep.

There's no perfect formula for circadian fitness but the best rule to follow is this: abide by the natural rhythms of the day whenever you can. Don’t do relaxing things when your system is supposed to be revving up for the day and don’t do intense things when your body is supposed to be winding down.



You are what you eat as they say, and this definitely applies to sleep. Starchy carbs, for example, have been shown to help people fall asleep faster when eaten several hours before bedtime… but only by about ten minutes. However if you eat too many refined carbs (i.e. 90% of carbs in America) and/or too much sugar this can seriously reduce the quality of your sleep. A diet high in RC’s and sugar has been shown to increase levels of insomnia and decrease levels of deep sleep so this is something worth considering.


Emotional state, body and room temperature, even social interactions—all these things affect your body clock, your circadian rhythms, and ultimately your sleep. I recommend looking into all of them; you never know what the X factor might turn out to be. Downing a triple espresso at 6:00pm or staring at your cell phone fifteen seconds before you close your eyes at night are obvious no-no’s, but it’s the not-so-obvious habits that might be the key for you. Like with anything else you can’t fix something if you’re not aware of it in the first place.


Ultimately getting proper sleep is about two things; if you do them consistently everything else tends to take care of itself:

1. allowing enough time for sleep

2. following the natural blueprint of the day

These are far from easy or automatic though. Modern life has put up some pretty big obstacles, whether it's the pressure to cram our schedules to the limit or the poor habits that are present all around us. But it’s all under your control if you care to control it. Armed with the right info you can remove these blockades one habit at a time, get yourself back into a more primal state, and recalibrate your whole sleep mechanism.

I hope this article has shed some light on specific steps you could be taking to improve your sleep or maybe reminded you of things you’ve been meaning to work on for awhile. The key is to start making small changes here and there that can end up paying big dividends for you. Like with all aspects of health it’s not about one individual thing but instead a collection of behaviors that all help to move the needle in the right direction. Trading out 30 minutes of social media time at night for a book, axing the second (or third) cup of coffee, stepping outside for a dose of morning sun without devices or distractions. Every little thing makes a difference. So make it your goal to pick up one healthy habit starting today.

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