The Basics of Circadian Rhythms

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Whether you’ve been jet-lagged or fallen asleep with all the lights on, you are probably familiar, at least physically, with what happens when you don’t rest in total darkness. Grogginess, disordered thinking, an increased appetite, even headaches, can be a sign that you didn’t get enough proper rest. The added disruption of light during your sleep cycle can wreak havoc on everything from your mood to your ability to make healthy choices.

Here’s why we need total darkness to sleep.

It’s all about those circadian rhythms

You may find that you naturally get sleepy at specific times of the day and that those are often tied to when the sun goes down. That’s not a coincidence, according to Bill Fish, the Bill Fish, Managing Editor of

“Our circadian rhythm is an internal 24-hour body clock that tells us when to rest and when to be alert. The key to our circadian rhythm is that it craves consistency. Because of this, we strongly recommend that you attempt to get to bed at close to the same time each night and wake each time each morning. This schedule and structure makes getting to sleep much easier each night,” Fish says.

Circadian rhythms, according to the National Institue of Health, are “physical, mental, and behavioral changes that follow a 24-hour cycle. These natural processes respond primarily to light and dark and affect most living things, including animals, plants, and microbes.”

These rhythms are primarily regulated by our hormones which increase and decrease throughout the day based on everything from what we eat, to how much sunlight we get. The word, “circadian” comes from the Latin, “circa,” meaning around, and “diem,” meaning day. Circadian literally translates to “around a day.”

Your brain regulates all these clocks together, and it’s referred to as the master clock, which is why your circadian rhythms can be totally disrupted by light.

The single most impactful thing you can do to change your circadian rhythm is to change your exposure to light. That’s why darkness is so important when it comes to getting a good night’s sleep.

What happens when your circadian rhythms get disrupted by light?

If you take on a different shift at work (like the graveyard shift), travel to a place that’s outside of your time zone, or just stay up later than usual binging Netflix, you’ll likely feel the impact of the disruption in your circadian rhythm the next day.

Short term, you’ll probably feel more tired, groggy, disconnected from your body, and you may experience more cloudy thinking. You’ll also find that you may be hungrier, even though you’re tired. That’s because your hormones have been thrown out of whack, and your body is trying to get you the energy you need to perform whatever daytime duties you have to do. Getting a little less quality sleep than usual isn’t call for alarm unless it becomes chronic.

Longer-term, a disruption in circadian rhythms can impact your overall health and well being.

A study done on mice and published in 2009 by the Society for Neuroscience showed that chronic disruption of the natural sleep and wake cycle can lead to everything from weight gain and impulsivity to slower thinking and other physiological and behavioral changes, similar to those observed in people who experience shift work or jet lag.

In addition to physical and acuity problems, a disruption of your circadian rhythm of wake and sleep, even by the addition of a small amount of light, can significantly impact your mental health and long-term brain health. A 2017 study in the American Journal of Epidemiology found that being exposed to even a small amount of light can increase depression, particularly in older adults.

How to improve your circadian rhythms

There are a few things that you can do to ensure that you are creating the optimal sleeping environment. Making your sleeping space dark, quiet, and cool are three things that can significantly improve your chances of enhancing your natural sleep and wake cycles. Yet, there are a few things that you can do specifically to ensure that you are not exposing yourself to unnecessary light both throughout the day and overnight.

Get enough daily sunlight

One of the critical ways to improve your sleep is to ensure that you get enough natural light by spending at least 20-30 minutes per day outside in the sunlight. This trick works great, especially if you get plenty of exposure early in the day.

Exercise regularly

As I mentioned before, exercise can change your circadian rhythms for a variety of your systems — and sleep is one of them. By getting enough activity in during the day, you can ensure that you sleep better at night.

Limit your electronic consumption at least one hour before bed

We’ve all heard and read about the impact that blue light can have on our mental and physical health, but did you know it can considerably disrupt your sleep, too? Blue light is particularly disruptive when you are trying to rest, so put your phone on night mode and pick up a book at least an hour before bedtime. Falling asleep, endlessly scrolling through Instagram is one sure way to disrupt your circadian rhythm.

Set and stick to a sleep schedule

If you’re a parent, you know how crucial regular schedules can be for your kids’ well-being. The same is true for yourself. Setting and sticking to a regular bedtime routine and sleep schedule can help support a healthy circadian rhythm and allow you to drift off to sleep when your body is ready. So whether that’s taking time to journal before bed, meditating as you drift off, or just getting as cozy as possible, be sure to make it a routine, and your sleep will improve.

Make it as dark as possible in your bedroom

Whether you choose to use an eye mask or invest in blackout curtains, finding a way to make it as dark as possible in your sleeping space is key. The best way to see if there is any light leaking through is to wait for night, turn out all your lights and see what draws your attention. Is there an alarm clock that emits light? What about your charging phone? Take account of any and all light leaks and do your best to either physically block them or turn them off.

If you opt for blackout curtains or a mask, remember that you’ll also need to invest in something to help naturally wake you up, too. Several illuminated alarm clocks slowly glow as it gets closer to the time to wake up. These can help you wake more rested rather than jolting you awake since they help regulate your circadian rhythm more naturally. Consider the entire course of sleep to figure out the best option for you.

If you follow these suggestions and your sleep-wake cycle doesn’t seem to improve, it may be time to try other avenues. If you find that your lack of sleep or disrupted sleep impacts your ability to do your job, changes how you interact with your family or friends, or if you notice that you’re feeling more agitated or depressed, it may be time to seek out a medical expert who can help you get to the bottom of your disordered sleep.

Read my story at Shondaland.

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Abigail Bassett is a full-time freelance journalist, content creator, and television, video, and podcast host whose work has appeared in publications like TechCrunch, Fast Company, Inc. Magazine, Forbes, Fortune, Motor Trend, Shondaland, Money Magazine, and on CNN. Her passion is telling unique stories that change the way we see, interact with, and relate to the world. She is also a Yoga Alliance Registered 500-hour yoga teacher.

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