What Is Circadian Rhythm?

Circadian Rhythm and Blues

Learn about the physiological process of circadian rhythm and how it impacts our sleep, from lifestyle, sleep and relationship expert, Lissa Coffey
Blog

Discover what circadian rhythm really is

Nature has a rhythm. We see it in the way the seasons change, the way the tide comes in and out, and the way the sun rises and sets. It all just happens as it is supposed to. But what exactly is a circadian rhythm? A circadian rhythm is the physiological processes of all living animals and plants within about a 24-hour cycle. This rhythm is created internally, but it can be modified by external factors such as temperature and sunlight. When we look at patterns of daily behavior, such as eating and sleeping, circadian rhythms are key.

The History of Circadian Rhythm

Back in the days before electricity, staying in rhythm with nature’s cycle was the norm. People would wake up with the sun, work in the daylight and go to bed sometime not too long after dark. It wasn’t that long ago that the few television channels we received signed off at midnight, and there was no programming overnight. But now, we live in a 24/7 world. We do business with foreign countries by computer at all times of the day and night. We travel across oceans and time zones in a matter of hours. We don’t have to wait for stores to open: we can shop online anytime we want. And between the thousands of television and radio stations we have access to, along with internet options, we are never lacking in around-the-clock entertainment. Given all the amenities of life that we have access to, it’s understandable how easily our own rhythms can get out of sync with nature.

Genetics Play a Role in Circadian Rhythm

Modern science has identified “chronotypes” among people. While habits play a role in this, a person’s chronotype, or internal clock, is most influenced by genetics and can be difficult to change. There are morning birds and night owls, and many others in between. We each have a chronotype that fits on a bell curve alongside everyone else’s. Thirty to 50 percent of people fall in the middle of this curve, sleeping between the hours of 11 p.m. and 7 a.m. About 40% of people have sleep cycles that fall about an hour or so down the sides of the curve, sleeping between 10 p.m. and 6 a.m., or between midnight and 8 a.m.

Then there are those who fall on the edges of the curve. Many teenagers tend to be in this category, as their changing hormones can affect their chronotype. They prefer to stay up later, and wake up later, though this pattern shifts earlier as they age. Because both science and educators have recognized this, some schools are now starting a bit later to help their students be more alert and productive during class times. With flex schedules, and more jobs available for nighttime workers, for some people it can be a benefit to be a night owl.

Having a sleep schedule that is outside the norm can be a problem, as society tends to reward early risers. The expression “the early bird catches the worm” dates back to the 1600s! For those who need to get to bed early and wake up early, it’s not so difficult to fit in. But those whose chronotype gives them the need to stay up late, and wake up late, often struggle conforming to the duties and expectations that come with a 9-5 job.

What Is Social Jet Lag?

When a person’s body clock is out of sync with society’s clock, scientists call it “social jet lag.” Social jet lag puts stress on the body and mind that can affect job performance and undermine health. Research shows that those with social jet lag were more likely to be overweight, had a greater risk for depression, and were more likely to participate in risky behaviors such as smoking or drinking. It’s not the chronotype itself that causes these problems; it’s the mismatch between the chronotype and the daily schedule. In addition, if night owls are getting less sleep because they are getting up earlier while not going to bed earlier, this ongoing sleep deficit can also create a risk for heart disease, diabetes and obesity.

Changing Your Internal Clock for Better Sleep

If night owls can’t change their work hours, there are ways that they can shift their internal clock to earlier in the day. However, this requires commitment and can be difficult to maintain.

One way to shift is through a combination of bright light therapy and melatonin. Usually being out in the sun provides the natural light exposure necessary for our internal clock. But when working from an office all day, we don’t always get the sun we need. There are lamps that mimic the sun that can be helpful. Leaving the curtains open at night so that the morning sun streams in is a good strategy, as is going for an early morning walk or run. With light therapy, you must stick to the same schedule every day of the week. If you sleep in on the weekend, you can set back all the progress you’ve made up to that point.

The body naturally produces the hormone melatonin at night when it is dark, but melatonin production varies from person to person. Taking a melatonin capsule 3-4 hours before the desired bedtime will help a night owl feel sleepier earlier than they usually do. Think of this new routine with light therapy and melatonin as a sleep diet, and be diligent with it.

Another option to reset the body clock is chronotherapy. Rather than trying to go to bed earlier than usual, night owls can try going to bed two hours later each night until they reach their desired bedtime. This process can be successful, but it takes about two weeks. Few people have such control over their schedules for that length of time to follow through with the plan.

Another strategy for groggy night owls is the midday coffee nap. When you feel tired, adenosine, a chemical that promotes sleep, circulates throughout the body. When you fall asleep, adenosine levels drop. Caffeine competes with adenosine, preventing it from being received by the brain. So, you feel less sleepy. Since it takes 20 minutes for caffeine to take effect, quickly drink a half a cup of coffee or so on your lunch break, then set your alarm for a 20-minute nap. This way, the body doesn’t get into the deep sleep state. You can also just rest or meditate during that time if you prefer. The caffeine starts to kick in at the end of the 20 minutes, and you also have the energy boost from the quick nap or rest. Just make sure that you don’t consume caffeine any time past 2 p.m., or you’ll have a more difficult time getting to sleep at bedtime.

Whether you’re a night owl or a morning bird, or anything in between, make sure the sleep you get, whenever you get it, is on a comfortable and supportive mattress. This way you’ll wake up refreshed no matter what time it is!

Do you know what circadian rhythm is? Learn more about how it impacts our sleep from @CoffeyTalk @BetterSleepOrg.

Sources:

This blog provides general information about sleep and sleep products. The words and other content provided in this blog, and in any linked materials, are not intended to replace a one-on-one relationship with a qualified heath care professional. This blog should not be construed as medical advice or used to diagnose, treat, prevent or cure any disease or condition. If the reader or any other person has a medical concern, he or she should consult with an appropriately-licensed physician or other health care professional. This blog is not a substitute for professional medical advice, diagnosis or treatment, and should not be relied upon to make decisions about your health or the health of others. Never disregard professional medical advice or delay in seeking it because of something you have read on this blog or elsewhere on bettersleep.org. If you think you may have a medical emergency, immediately call your doctor or dial 911.

 

Want Better Sleep?

Get updates from Better Sleep Council
to make all your dreams come true.

You have Successfully Subscribed!