What Is Circadian Rhythm?

You may have heard about the importance of keeping your circadian rhythm in check to improve your sleep quality and keep your body healthy. But what exactly is your circadian rhythm and how does it affect your sleep cycle?

We’ll walk you through everything you should know about your body’s biological clock, including how it works, factors that can throw it off, tips for improving it, and sleeping disorders that can result from a disrupted circadian rhythm.

What Your Circadian Rhythm Is and How It Works

Yourcircadian rhythmVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View sourceis your body’s clock regulating your sleep and awake cycles throughout the day. Just like animals, humans’ circadian clocks are sensitive to light and dark, as well as hormones, which help trigger the desire for sleep.

Every tissue and organ in your body follows a biological clock or circadian rhythm whichis synchronizedVerified Source ScienceDirectOne of the largest hubs for research studies and has published over 12 million different trusted resources.View sourceby your brain’s master clock. This master clock helps regulate all of your internal circadian rhythms, keeping your body working effectively over a 24-hour period.

Located in the suprachiasmatic nucleus (SCN) that ispart ofVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View sourcethe brain’s hypothalamus, your body’s master clock (sometimes called your circadian pacemaker), will send signals throughout your body during the day to help regulate this cycle.

When your circadian rhythms are in sync with your body’s master biological clock, your sleep tends to be more regular and restorative. But, when out of alignment, your sleep may suffer and lead to sleep disorders.

Difference Between the Biological Clock and Circadian Rhythm

Though the two are used synonymously, your biological clock is different from your circadian rhythm. For instance, humans have multiple circadian rhythms throughout their body that are all regulated and kept in check by your body’s master clock.Verified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View sourceSo, while in sync, they are a bit different.

It’s easiest to see the difference between the two when looking at plants. Unlike humans, plants have a biological clock that adjusts with the seasons, rather than a 24-hour circadian cycle.

How the Circadian Rhythm Affects Your Body

Your circadian rhythm impacts different parts of your body. While it plays a large role in your sleep cycle, it has alsobeen connectedVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View sourceto metabolic changes, blood sugar processes, and your cholesterol levels, which when out of sync can lead to weight loss or gain.

There’s also evidence to suggest that your circadian rhythm plays a key role in how effective your immune system is. In fact,some researchVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View sourcesuggests your circadian rhythm (when working properly) can aid anti-cancer drugs in providing treatment.

Lastly, your circadian rhythm can also influence your mental health, which comes as no surprise since sleep quality and mental health are often so closely linked. Your body’s clock having anirregular circadian rhythmVerified Source Harvard HealthBlog run by Harvard Medical School offering in-depth guides to better health and articles on medical breakthroughs.View sourcecan impact your risk of depression, bipolar disorder, dementia, and other mental disorders.

Circadian Rhythm and Sleep

While your circadian rhythm can help keep your entire body in check, it plays a significant role in our sleep. In fact, usually when you hear the term ‘circadian rhythm’, people are referring to your sleep health, even though there are multiple circadian rhythms that regulate parts of our daily lives.

Since your body’s clock is needed to help regulate your sleep and awake cycle, it’s understandable that sleep would be heavily influenced by your circadian rhythm. Light and darkness are the two most prominent signals that will help determine your sleep-wake cycle.

When you see light, your brain sends signals to the rest of your body to become alert, helping you wake up and remain awake throughout the day. When it’s nighttime, your body responds to the lower light by producing melatonin naturally, helping you become sleepy, and keeping you asleep throughout the night.

This circadian rhythm is what happens when your body is in alignment with your master clock. However, your circadian rhythm can be thrown out of sync — and this can lead to sleep issues.

What Interferes with Your Circadian Rhythm

Your circadian rhythm is sensitive and can be disrupted in many ways. Your rhythm might be thrown off for the short-term, say a night or two, or for the long-term, several months or years, depending on the interference and whether or not it becomes recurrent.

A short-term disruption could be as simple as not waking up on time and keeping blue lights like screens on late at night. Jet lag is another example. When you cross a time zone, it can take your body a day or two to adjust to the new light/dark circadian rhythm in your setting. This is typically temporary, but flight attendants, pilots, and anyone who travels across time zones frequently for work may experience this disruption as more of a long-term symptom.

Another example of a disruption to your body’s circadian rhythm is shift work. This could happen if you work the second or third shift, so from late afternoon to evening or late at night to the morning.

This type of work throws off your body’s responses to light and darkness, and can wreck your sleep cycle. While it’s possible for your body to adjust to this new sleep pattern, many shift workers experience sleep disruptions caused by this shift in their circadian rhythm.

Sleep scientist Dr. Jing Zhang emphasizes that not having enough natural light exposure during daytime and having too much artificial light during night time can be detrimental to your circadian rhythm.

If you’re a night owl (which, most of the population is not), you may also experience interferences in your circadian rhythm. Some people naturally stay up late and prefer to wake up earlier in the morning. This disorder, also known as delayed sleep phase disorder, primarily impacts teenagers, and not much is understood about why it occurs or how to rectify it.

The reverse may also be true. Advanced sleep phase disorder is categorized by those who find themselves falling asleep early in the evening and waking up very early in the morning, likely before it is light outside. Since this falls outside of the normal circadian rhythm, adults with this disorder may also experience sleeping issues.

Those who are blind or visually impaired may also experience sleeping issues due to their circadian rhythm if they’re unable to see light. Others may not have a consistent sleep schedule or cycle due to a medical condition or lifestyle factors, which can also interfere with their body’s circadian rhythm and make it harder to get quality sleep.

What Happens to Your Body When Your Circadian Rhythm Is Off?

Simply put, when your circadian rhythm isn’t functioning properly, it can throw off your body’s regulation. This includes throwing off your sleep cycle. You may find it difficult to fall asleep at night, struggle to wake up in the morning, or find yourself waking up throughout the night and unable to easily go back to sleep.

In addition, some studies have shown that those experiencing an out-of-sync circadian rhythm may experience lesser sleep quality. They may not sleep as deeply or get enough restorative NREM sleep per night, which can lead to additional issues associated with long-term sleeping disorders.

Those with circadian rhythm issues are also at a higher risk of developing a sleeping disorder like insomnia or circadian rhythm sleep disorders, each of which has its own associated risks.

Other processes in your, including your metabolism, weight, and immune system could also be affected when your circadian rhythm is off.

Dr. Jing Zhang points out that circadian disruptions are associated with an increased risk of cardiovascular diseases, including hypertension, which is often overlooked.

Ways to Keep Your Circadian Rhythm Healthy

Preventing your circadian rhythm fromgetting out of syncVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View sourceis important if you want to promote good health and sleep. While it may seem out of your control, particularly if you’re a shift worker or someone with an abnormal sleep schedule, there are actually some tips you can follow to promote a healthier circadian rhythm.

Create a regular sleep schedule. If you’re struggling to fall asleep on time, one of the best ways to get your circadian rhythm back on a regular schedule is to set a sleep routine. Decide what time of night works best for you to fall asleep and to wake up. Then, try to stick to it — even on weekends.

For example, maybe going to bed at 10pm and waking at 6am works best for you. If you need to alter this by an hour on the weekends, this should be fine, but once your body is used to the routine, you may find yourself getting tired as 10pm approaches.

Even if you find it hard to fall asleep at your set bedtime, it’s important you stick to this schedule.. Be consistent, even if you’re not feeling particularly tired one night. This will help cue your circadian rhythm that it’s time to go to sleep, even if it takes a few weeks for your body to catch on.

Reduce light and screens in the evening. It’s safe to say most of us are on our phones more often than we’d like. If you think your screen time may be throwing off your sleep schedule (and it can), limit screen time in the evenings. While mindlessly disconnecting as your TV blares may sound like a good step to make you sleepy, the blue light your TV screen emits may make it more difficult to fall asleep.

Ultimately, you should do what works best for your body, but if you watch a lot of TV at night or find yourself constantly scrolling social media, this may be the culprit preventing you from falling asleep. Try omitting screens an hour or two before your bedtime (even get the TV out of the bedroom if you can) and read in bed or try to unwind during this time before sleep, instead.

Get sunlight throughout the day. Exposing your body to sunlight not only helps you get the necessary Vitamin D your body needs — it’s also a good way to help keep your circadian rhythm responsive.

This could be as simple as opening your blinds or curtains in the morning to let the light in, sitting outside on your porch, or going for a quick walk upon waking up. Doing this can help trigger your circadian rhythm’s natural cues to daylight and help you become more energetic during the day and sleepy at night.

Exercise regularly. We all know exercise is good for us, but squeezing it into our busy schedules can be difficult. However, regular exercise and physical activity is good for your body’s overall health — and it can help support your circadian rhythm.

You don’t have to create a rigorous fitness schedule or join a gym to experience the benefits either. A brisk walk in the morning or evening, quick running session on an at-home treadmill, or even dancing to your favorite playlist is enough to help your body burn some calories, stay energized, and keep your circadian rhythm in line.

Limit caffeine. If you fear caffeine may be the culprit keeping you awake at night and throwing off your circadian rhythm, don’t panic. You don’t have to eliminate your daily cup of coffee, but you can try to limit the amount of caffeine you take in each day.

First, consider everything you drink or eat that may contain caffeine: coffee, tea, chocolate, macha, etc. Then figure out when you’re consuming these beverages or foods. If you like an afternoon cup of coffee, opt for water instead. Or, try switching to half or full decaf.

If you drink caffeinated tea later in the evening, you may try scaling back or drinking it earlier in the day. Of course, you can try eliminating caffeine entirely from your daily routine, but you may find this process more frustrating and less enjoyable.

Don’t nap, if you can help it. However, there is evidence suggesting the health benefits of napping when it’s carefully timed. If you favor an afternoon or early evening nap (and let’s be honest, who doesn’t?), try to scale back the amount of time you’re napping to 10-15 minutes. Or, if you can, plan to power nap earlier in the day.

Falling asleep for too long or later in the day can throw off your circadian rhythm. While it’s best to avoid naps, if possible, if you feel like a power nap for productivity is needed, make sure you only sleep for a small amount of time to prevent issues at night.

Of course, if you had an off day and didn’t sleep the night before, get the rest your body needs, then start fresh the next day.

Talk to your doctor. If your circadian rhythm is out of sync, it can lead to sleeping disorders that need medical treatment. If you’re struggling to fall or stay asleep regularly, or if your sleep problems are interfering with your daily life, you should always talk to your doctor. There may be other underlying symptoms leading to sleep trouble that your doctor can diagnose.

Don’t try to supplement or treat your symptoms on your own. It’s always best to get a thorough check-up to make sure your sleeping issue is addressed properly and let your doctor recommend potential solutions. These solutions may be as simple as melatonin supplements available or the counter or they may require more specialized treatment.

FAQs

How do I fix my body’s circadian rhythm?

Adjusting your body’s circadian rhythm requires consistent efforts to align with a healthier sleep-wake cycle. Start by establishing a consistent sleep schedule, going to bed and waking up at the same time each day, even on weekends.

Exposure to natural light during the day, especially in the morning, helps regulate your circadian rhythm, so spend time outdoors if possible. Limit exposure to artificial light, especially in the evening, and create a calming bedtime routine to signal your body that it’s time to wind down.

What is the best time to sleep for my circadian rhythm?

The best time to sleep for your circadian rhythm is usually when your body’s core temperature drops, signaling the onset of sleepiness. This typically occurs in the evening, around 10 pm to midnight, but individual variations exist. Listen to your body’s natural signals and adjust your sleep schedule accordingly.

How do I know if my circadian rhythm is off?

Signs of an off-kilter circadian rhythm include difficulty falling asleep at night and excessive daytime sleepiness. Additionally, mood swings, irritability, and changes in appetite can also be indicators of a disrupted circadian rhythm. If you consistently struggle with these issues, consider consulting a healthcare professional to identify underlying causes and receive tailored advice.

How long does it take to change the circadian rhythm?

Changing your circadian rhythm takes time and persistence. It can vary from person to person, but generally, it may take a few weeks for your body to fully adjust to a new sleep-wake cycle. Be patient and stick to your adjusted schedule consistently.

How do I find my natural circadian rhythm?

To find your natural circadian rhythm, pay attention to when you naturally feel sleepy and alert. Note the times when you feel most energized during the day and when you naturally start to wind down in the evening. This self-awareness can guide you in establishing a sleep schedule that aligns with your body’s natural tendencies, promoting better sleep quality and overall well-being.

The Bottom Line

Your circadian rhythm is responsible for keeping your body running regularly and promoting a healthy sleep cycle. If it’s off, your overall health may suffer and you may struggle to fall or stay asleep.

While there are strategies you can follow to promote a healthier circadian rhythm, you should reach out to your doctor if your sleep quality declines or begins to impact your day-to-day activities.