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In 2007 the World Health Organization declared shift work a probable carcinogen. Yeah, you read that right: working at the wrong time can kill you.
And cancer isn’t the only problem it causes. If horror movies don’t give you nightmares, the list of health problems associated with shift work will. So what’s the deal here?
Shift work messes with your circadian rhythm. Now “circadian rhythm” might sound to some like iffy pseudoscience. Far from it. It has so much credibility that it has incredibility. Michael Rosbash won the Nobel Prize in medicine in 2017 for his work on it.
There are no two ways about it: humans are diurnal. We’re designed to be awake when it’s light out and asleep when it’s dark. Sure, we can be nocturnal but we weren’t built for it and if you stay on that schedule too long, things get wonky.
Well, anyway, good thing we’re not shift workers, right?
Problem is, these days all of us basically are.
From The Circadian Code:
Professor Till Roenneberg, a researcher in Munich, surveyed more than 50,000 people in Europe and the United States and found that the majority of people either go to bed after midnight or wake up early with insufficient sleep. Similarly, people also follow different bedtime schedules on weekdays and weekends.
This, combined with our bright screen use at night, means we’re all living like shift workers to some degree. And our bodies weren’t built for this. As we discussed in my recent post on exercise, the way we live our modern lives has “some problems” in the same way the Pacific Ocean has “some water.”
Timing matters in life, even more than you think. We’re not talking about clever productivity hacks here; we’re talking about much more important stuff like your health. And biology doesn’t like to negotiate. For your body, “no” is a complete sentence. So what do we do?
Luckily, experts have answers. I went down the research rabbit hole and patched together insights from a number of fancy-pants sources: Satchin Panda at the Salk Institute for Biological Studies, Daniel Lieberman at Harvard, and Andrew Huberman at Stanford. They’re gonna tell us how to get our circadian rhythm back on track for increased health, happiness and productivity.
Let’s get to it…
Every cell and every organ in your body has a clock. And, if things are going right, they’re synced up with the master clock in your brain: the SCN or “suprachiasmatic nucleus.” Think of it like an old school heist movie: “Synchronize watches!”
Because if things aren’t in sync, your body is like a bad symphony. But instead of the bassoon and viola coming in later than they should, it’s your hormones that are out of whack, leading to problems with energy levels, hunger, stress and overall health. This is, as they say, “important.”
Brass tacks: what is the most important factor when it comes to your circadian rhythm? Light. Our ancestors didn’t have a lot of control over light. When the sun rose and set was not a very democratic process. We, however, have unprecedented control over the amount and timing of the light we’re exposed to, leading to unprecedented problems. And this is why we’re all shift workers now.
Okay, clearly not good. So what do you need to do tomorrow morning to fix this? Uh, back up, fella. Tomorrow is too late. Most of the work has to start the night before.
From The Circadian Code:
Your performance at any moment during the day is primarily determined by what you did the night before—when you ate and how much you slept—because that is what sets your clock, which then primes your body and brain.
Sounds akin to: “All battles are won or lost before they are ever fought.” I guess Sun Tzu was a circadian expert.
(To learn more about how you can lead a successful life, check out my bestselling book here.)
So what do we need to do tonight to get everything back on track? Well, you’ve probably heard some rumblings about the evils of blue light. Actually, that’s only partially true…
Blue light sends the most powerful signal to your SCN that it is daytime, making it your worst enemy at night — but it’s not the only enemy. After dark, you want to reduce all light as much as possible.
Light at night means less melatonin which means poor sleep which results in a foggy brain the next day. (Researchers have spent many sleepless nights studying this stuff.) Optimally, you want as little light as possible after 8PM. Sound unrealistic? Oh, it is. Hold on, it gets worse.
I regret to inform you that as the day goes on, your retina actually becomes more sensitive to light. Indoor lights and screens that aren’t powerful enough to wake you up and set your clock in the morning are more than enough to screw your clock up at night.
From The Circadian Code:
A mere 8 lux—a level of brightness exceeded by most table lamps and about twice that of a night-light—has an effect, notes Steven Lockley, a sleep researcher at Harvard.
No, I’m not saying you need to sit around during the evening with your home as dark as a Nietzchean abyss, skulking about like a swampgoblin. I am well aware that nothing short of an EMP blast is going to stop us from watching TV and doing internet ablutions on smartphones. We just need to limit light as much as we reasonably can, and there are tricks we can leverage to help.
The cells in your eyes most relevant to timing are primarily at the bottom of your retina — so you want to reduce overhead lighting. Dim lights set low in a room are a good idea. (And candlelight does not trigger these cells much at all.)
Use the “Nightshift” feature on Apple devices (or the equivalent) to reduce blue light. And if you want to go for the nuclear option, check out Drift TV, which gradually removes blue light from your television screen at night.
I know what some people are thinking: “Oh, that won’t work for me. I’m a night owl.” Ummm, maybe not.
I’ve been a card-carrying night owl my entire life. Everybody talks about the early bird, but I have always lived in fear of being the early worm. Telling me I should go to bed early makes me want to reach for something sharp. I thought it was just how I was wired. Guess what? I was wrong.
Researcher Ken Wright Jr. at the University of Colorado, Boulder, did a study where he took night owls camping. No artificial light. Guess what happened? Yup. In a matter of days they stopped being night owls and were all in bed by 10PM.
Maybe you’re an exception, but to my chagrin, I’m not. Keeping the house dark at night, through some sort of Blakean alchemy, has transformed this night owl into an early riser. You might want to give it a shot.
(To learn how to make emotionally intelligent friendships, click here.)
Okay, light is the number one thing when it comes to getting our clocks right. But it’s not the only thing…
Eating is another signal that tells your body it’s daytime. Also, there’s plenty of research on how healthy “time-restricted eating” is and, yes, it looks like those intermittent fasting folks are on to something. Satchin Panda found that people who got all their calories in an 8-11 hour window and stopped eating 3 hours before bed were notably healthier.
I know, I know — late night snacks are one of the things that makes life worth living. I agree. But if we sacrifice the unmitigated glory of munching after dark, what benefit do we get?
Super productivity and focus.
From The Circadian Code:
Studies have shown that both modest fasting and exercise have a similar brain-boosting effect. Each of them can increase a chemical called brain-derived neurotropic factor (BDNF) that improves the connection between brain cells and improves brain function. When you have plenty of BDNF combined with a good night’s sleep, your brain is better prepared for performing complex tasks, staying focused, and being productive, so you can complete the same amount of work in less time. Eating a late-night meal negatively affects your ability to pay attention the next day.
(To learn the two-word morning ritual that will make you happy all day, click here.)
Okay, everybody says getting enough sleep is important. Definitely true. But when it comes to your circadian rhythm, it’s not just about the amount…
You need around seven hours of sleep. More for kids, less for older folks. Sleeping notably less — or more — than seven hours is associated with a shorter lifespan.
…numerous studies using better data and sophisticated methods to correct for factors like age, illness, and income have confirmed that people who sleep about seven hours tend to live longer than those who sleep more or less. In no study is eight hours optimal, and in most of the studies people who got more than seven hours had shorter life spans than those who got less than seven hours (an unresolved issue, however, is whether it would be beneficial for long sleepers to reduce their sleep time).
But the thing that very rarely gets talked about is consistency. It’s huge. Studies show kids that sleep a consistent amount every night get better grades.
Timing and consistency is a good idea across the board. Having a regular schedule for when you wake up, when you have your first and last meal, when you dim the lights, and when you go to sleep is a powerful combo. Satchin Panda says if any of these factors shift by two hours over the course of a week, it’s an issue. If they all do, that’s a big issue.
(To learn how to live a long awesome life, click here.)
Okay, we have our evenings down. But what’s important when you wake up in the morning? Well, turns out what you do then is the most important factor of them all…
Satchin Panda’s words, not mine: “When (and how) you wake up is the most important event of the day.”
And the key event here is getting bright light in your eyes early to set your master clock. If your only outdoor activity is collecting Amazon packages from your doorstep and you tend to get as much morning light as a mole rat, take note. Live like a Morlock and you’re going to be less chipper, less energetic and the word “metastatic” may be in your future.
From The Circadian Code:
In modern times, an average person spends more than 87 percent of their time indoors; we average only 2½ hours outdoors, half of which is often after sunset. Our indoor light environment may be disrupting our circadian rhythm and compromising our mood.
So if you forget everything else I have written here, remember this:
Right after you wake up, go outside and get sunlight into your eyeballs.
Yes, you need to go outside. Remember, your retinas are more sensitive at night, meaning they are less sensitive in the morning. You need ~100,000 lux before 9AM. Don’t worry, that only takes about 2-10 minutes depending on how bright it is outside. But digital screens are only 500-1000 lux and that just ain’t enough photons.
It’s important to get this as early as possible to set your clock properly. The relevant cells in your eyes are awfully particular. They respond best to light at “low solar angle.” So once the sun is overhead, it’s not the same. Blue light in the morning is a good thing, so appreciate that morning sky.
No, do not stare directly into the sun. The negative effects of this are obvious: you will be blind and unable to read my future blog posts.
(To learn the 4 harsh truths that will make you a better person, click here.)
So your clock is set. Once you’re firing on all chronological cylinders, when will you be sharpest and most productive during the day?
You’ll be sharpest between 10AM and 3PM. This is when you want to do your thinky work.
From The Circadian Code:
Your optimal brain function is highest between 10:00 a.m. and 3:00 p.m.; that’s when you should notice that your best work or learning is done. Studies have shown that this is the window during which we are in the right frame of mind for making good decisions, solving multifaceted problems, and navigating complicated social situations.
Still not feeling awake? Kinda cranky? You may need even more early sunlight. Indoor light isn’t enough to get your brain up to top speed during the day (but it sure is enough to screw you up at night.)
From The Circadian Code:
You need at least 1 hour of daylight exposure—being outside, driving in your car, sitting by a window where you can soak up at least 1,000 lux of light—to reduce sleepiness, synchronize your clock, perk up your mood, and stay happy and productive throughout the day.
(To learn how to stop being lazy and get more done, click here.)
What about when sunlight isn’t enough? Still tired throughout the day? Well, there’s another powerful influence on your circadian rhythm that can help…
Exercise has a huge effect on how well you sleep at night and how energetic you feel the next day.
One survey of more than twenty-six hundred Americans of all ages that controlled for factors like weight, age, health status, smoking, and depression found that those who regularly engaged in at least 150 minutes of moderate to vigorous activity a week not only reported a 65 percent improvement in sleep quality but also were less likely to feel overly sleepy during the day.
The most important thing about exercise is just to do it at all. That said, timing still helps. Doing it early in the day improves energy levels and mood but the optimal time is between 3PM and dinner. So, if you can swing it, try to work out between finishing work and eating your final meal.
An intense workout later at night can spike cortisol and mess with sleep, but if you can’t hit the gym earlier, there’s a hack that can help. Eating and exercising primarily alter circadian rhythm by increasing body temperature, so if you do either one late but still want a good night’s sleep, the trick is to take a shower before hitting the sack. This will help your body cool down and get ready for beddy-bye.
(For more on how to motivate yourself to exercise, click here.)
Okay, we’ve covered a lot. No longer can anyone say you don’t have rhythm. Let’s round everything up and learn the secret to how you can enjoy (a little) extra light and screen time at night without wreaking havoc…
Timing matters. Here’s what to do:
Yes, you really should do this every day. I don’t make the rules. The only part of life where you get time off for good behavior is prison. That said, there is a trick for sneaking in a little extra screen time in the evening without causing problems.
Stanford University professor Andrew Huberman says getting outside for 2-10 minutes around sunset can help keep your internal clock calibrated. A little more of that low solar angle magic light tells your SCN “must be nighttime” and can help defend against the negatives of evening light.
Yes, medical science insists you enjoy more sunsets.
No doubt, in the modern world, keeping your circadian rhythm humming properly can be challenging. But it’s worth it to feel more energized and happy during the day, to sleep better at night and give yourself a much better shot at long term health. We’re often our own worst enemy, and that also means we’re our own worst victim.
Timing is everything in life but we’re often too focused on the timing of external things when the really important stuff is internal.
So synchronize watches. This heist is an inside job.
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