Beating Fatigue with Circadian Rhythms

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Is getting out of bed in the morning a groggy struggle against the urge to just lie down and conk out for another hour or five? Or do you notice an energy crash midafternoon, only to find yourself unable to fall asleep when bedtime finally comes?

If that sounds familiar, then you might be having trouble with your circadian rhythms, the natural cycle of hormones that governs when you’re awake and when you’re asleep. Normally, this is driven by the changes in the light cycle over the course of each day:

  • In the morning, bright blue-toned sunlight reduces the production of melatonin, and you feel awake and ready to go.
  • In the evening, the softer and more reddish light stimulates the production of melatonin, so you start getting sleepy.

Human bodies are designed for this pattern of light exposure – back in the day, before we had the option of electric lights, this was all we could get. Just like we evolved to eat certain foods, we also evolved to live with certain types of light at certain times.

Unfortunately, today we’re constantly fighting these ingrained hormonal rhythms. Just imagine what happens when you stay up late with that bright, blue-lit computer screen glaring in your eyes. Even though you might feel tired, melatonin production is still suppressed thanks to all the blue light. This creates that “tired but wired” feeling of being exhausted but unable to drift off. And lying awake at night cuts into your sleep time, making you grumpy and tired the next morning.

This is awful to live with, and chronic sleep debt also has serious long-term consequences, including heavy-hitters like weight gain, metabolic problems, and faster aging. In fact, it’s a very close contest which is worse for your health: a pizza or an all-nighter. So here’s how to make sure you get the right spectrum of light at all times: blue light in the morning, and orange-red light in the evening.

Get Blue Light in the Morning

Even though it doesn’t look “blue” to us, morning sunlight is shifted towards the blue end of the visible light spectrum (just like computer and TV screens). Blue light suppresses the production of melatonin, which makes you feel awake and alert. In fact, this study found that blue light was just as effective as caffeine for waking up tired drivers! And this one found that office workers who worked under “blue-enriched white light” had higher levels of alertness and performance.

Because blue light is our natural signal that it’s time to get up and go in the morning, your goal should be to get blue light exposure early in the day. This is easy enough in the summer (when it’s light outside by the time the alarm rings), but on darker days, during storms, or if you can’t get outside, it’s not so simple. Here are some tips:

  • You can get sunlight-spectrum lamps for your home or office; it’s easy enough to just get one and leave it on in the background. In fact, you can even get these lights built into an alarm clock, to simulate “dawn” at whatever time you need to get up.
  • Your computer screen or even your phone can function as a “blue light” in a pinch.
  • If you’re feeling exhausted or drained in a windowless office building, try getting outside for a walk during lunch, to give yourself some blue light exposure.

Avoid Blue Light in the Evening

The flip side of all this is that when you don’t want to be alert and energetic, you’ll want to avoid blue light. Remember how blue light was as good as caffeine for waking people up? You know you wouldn’t sleep well if you were guzzling coffee right up until bedtime, so why would you stare at the computer screen all the way up until you hit the sack?

Back in the day, this was all taken care of for us: sunlight changed from blue to red around sunset, and our only options for illumination were various forms of firelight (also in the red side of the spectrum). But today it seems like everyone is in a contest to see how much blue light they can cream in between dinner and bedtime: quick, go sit in front of the TV with your laptop, your tablet, and your phone, under a fluorescent light, to make extra sure you have a terrible sleep tonight.

This is bad news: nighttime light exposures has been associated with depression, diabetes, and other metabolic problems involving a whole range or hormones – not to mention, obviously, fatigue the next morning.

Ideally, the way to combat this is by banning electronics from your precious retinas for at least an hour before bedtime. But when that just isn’t going to happen, here are some alternatives:

  • F.lux: f.lux is a free download that automatically shifts your computer’s color display in a warmer direction during the evening. It’s the quickest and easiest way to make your laptop easier on your eyes and on your hormones – go download it!
  • Orange glasses. They might look a little dorky, but orange glasses can protect your eyes if you have to be looking at a bunch of different screens, or if you’re just disturbed by ambient blue light from fluorescent lamps or streetlights.
  • Warm-hued lightbulbs: if you spend a lot of time in one particular room during the evening, consider getting an incandescent or warmer-colored light bulb for that room.

It’s also important to remember that blue light can have this effect even if you aren’t looking directly at it. This study found that the blue light effect worked even through closed eyelids. This suggests that it’s not enough to just avoid computers before bed; you’ll also want to get them out of your bedroom: don’t leave glowing screens around when you’re asleep. If you can, put up blackout curtains in your bedroom to block out light from the street.


Summing it Up

Getting the right type and amount of light exposure is one of those problems that we can thank the modern world for making us deal with. But fortunately, the same modern technology that disrupts our circadian rhythms so dangerously can also give us the tools to re-align them: blue lights to help us wake up in the morning, and orange-tinted glasses, light bulbs, and other tools to let us wind down in the evening.

Nobody can really do this perfectly – even the most dedicated people sometimes find themselves stuck in an emergency, staring at a glowing blue computer screen long after they should have been in bed. But it’s not the one emergency that really hurts; it’s the chronic, day-to-day exposure. If you can get into the habit of usually taking precautions to make your light environment healthy and safe, your body will thank you many times over, in the form of up-and-at-em mornings, steady energy throughout the day, and pleasant evenings of drifting off to sleep rather than lying awake worrying about all the rest you’re missing out on. And that’s all without mentioning the chronic problems you’ll avoid down the line. If you could get all that for the price of some orange glasses and a quick walk outside once in a while…why wouldn’t you?

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