What is Your Circadian Rhythm, and Why is it Important?

Hourglass reflecting setting sun on windowsill

We all have our unique routines and rhythms that help us get through our day. Maybe you exercise or take a shower right after you wake up, get dressed, get coffee, then start work. Afterward, you probably try to relax and wind down for the day before you go to bed. You may not realize it, but our bodies are the same— they follow a biological rhythm that gets us through each day called the circadian rhythm.

You probably hear a lot about your circadian rhythm and how it helps you sleep, but you may not be familiar with what it actually is or how it works. Similar to how you follow a certain schedule during the day, your circadian rhythm does as well. This internal clock helps your body wake up and function properly throughout the day before winding down for sleep each night.

Of course, there’s a lot more to your circadian rhythm than waking you up and helping you sleep— like other areas of our body, it’s possible and not uncommon for our circadian rhythms to be in disorder, which can cause problems day or night. Before we get into that though, let’s dive into what the circadian rhythm is, and why it’s important to how you function.

What is your Circadian Rhythm?

A circadian rhythm is a 24-hour cycle that your body perpetuates, which helps your body work properly. Circadian rhythms aren’t just present in people— they exist in all types of organisms, from people to animals, and even plants and microbes. However, circadian rhythms aren’t the same thing as a biological clock— rather, biological clocks are an organism’s “natural timing devices,” which regulate the cycles of circadian rhythms. Circadian rhythms are affected by one’s biological clock, and can change seasonally as the environment does, or adapt to our bodies’ needs as we age. 

Our circadian rhythms are controlled by a part of our brains called the Suprachiasmatic Nucleus (SCN). Your circadian rhythm affects a number of biological processes including your sleep-wake cycle, your immune system, as well as your physical and mental health.

Exposure to light is the most important external factor that influences a person’s circadian rhythm. In fact, prior to the invention of artificial light and electronic devices, our circadian rhythms were influenced entirely by the sun. This 24-hour cycle wakes us as the sun rises in the morning, and helps us sleep as it sets each evening.

How Does Your Circadian Rhythm Affect Sleep?

As I mentioned above, your circadian rhythm is responsible for regulating your sleep-wake cycle. Your brain produces melatonin in the pineal gland, producing more during the morning and day, and less in the evening and night. When all is working as it should be, you should feel changing levels of alertness in the morning and day, and feel increasing levels of sleepiness as you get closer to bedtime.

However, a disrupted circadian rhythm can be responsible for sleep disruption as well, contributing to sleep disorders such as sleep deprivation, excessive daytime sleepiness, and delayed sleep phase disorder.

Your circadian rhythm is vital to getting a good night’s sleep, and a good night’s sleep is important to a healthy circadian rhythm. A circadian rhythm disorder can ruin your rest and throw off your body’s natural equilibrium in the process. Now that our systems aren’t influenced wholly by the sun, there is a much higher chance we could accidentally be disrupting our circadian rhythms and sabotaging how we function.

What Can Cause Circadian Disruption?

In our modern world, there are a lot of things that can throw the body’s internal clock off-kilter, preventing us from reaching the restful REM sleep we require to feel our best in the morning. Factors that can create a disrupted circadian rhythm can include:

  • Jet lag
  • Daylight Savings Time
  • Irregular sleep schedule or Changes in Sleep Pattern
  • Light Exposure inhibiting melatonin production
  • Shift Work Disorder

A recurring theme here is inconsistency. I’m sure we’re all familiar with how jet lag and Daylight Savings Time can throw our sense of time out of whack. The time changes we experience when we travel or when we set our clocks forward or back conflict with the schedule our internal clocks have come to know, creating disruptions in our sleep cycle.

Similarly, inconsistent sleep patterns or odd work hours can have a major impact on your circadian rhythm, keeping you awake when you want to sleep, or encouraging you to sleep when you want to wake up.

Thankfully though, there are easy lifestyle changes we can make to ensure that our circadian rhythms are working as they should year-round, and that we are getting the restful deep sleep that we need each night.

Tips for Maintaining a Healthy Circadian Rhythm

Your circadian rhythm and your lifestyle work in tandem with each other— your circadian rhythm helps create your lifestyle, while your lifestyle influences how well your circadian rhythm functions. A healthy lifestyle contributes to a healthy circadian rhythm, so consider the following if your circadian cycle is imbalanced.

Maintain a Regular Sleep Schedule

Consistency is key to maintaining a healthy circadian rhythm. You can adjust your circadian rhythm to fit your desired sleep-wake cycle by waking up at the same time each morning, as well as going to bed at the same time each night. If you need to nap during the day, make sure you don’t nap too close to your bedtime, or for too long— this can hinder your ability to get a full night’s rest at your proper bedtime.

I recommend falling asleep according to your chronotype’s sleep schedule. Our sleep schedules can hugely vary depending on our chronotypes, and it can be unproductive to force yourself to sleep when your body is trying to keep you awake. To identify your chronotype and find your ideal sleep schedule, check out my chronoquiz.

Proper Sleep Hygiene

Combined with a regular sleep schedule, appropriate sleep hygiene can go a long way in helping with any sleep problems you may be experiencing.

Avoid consuming caffeine or alcohol too close to your bedtime. The stimulant effects of caffeine can prevent you from falling asleep, and consuming caffeine within 6 hours of bedtime can reduce your total sleep time by up to 41 minutes. Consuming alcohol can contribute to sleep disorders, as well as cause snoring by relaxing the tissue in your throat.

Relaxation techniques such as breathing exercises, meditation, and guided imagery are also effective in helping you unwind each night before bed. I recommend the Power Down Hour, where you can finish your day’s business and get ready for bed in three twenty-minute increments.

Be Mindful of Light Exposure

Light exposure helps start our circadian rhythms each morning, but too much light in the evening, particularly from artificial lighting or our favorite electronic devices, can contribute to circadian disruption. In fact, the blue light produced by devices like our phones, computers, and TVs can inhibit the production of melatonin in our brains, which can inhibit our ability to fall asleep or stay asleep. I recommend not using any electronic devices at least 60 but preferably 90 minutes before bed each night to give your brain enough time to produce the melatonin you need to rest.

Alternatively, bright light therapy can help treat circadian disorders by “resetting” your internal clock if it’s not working properly. This is done by exposing your eyes to intense, but safe amounts of light for usually around 20 to 30 minutes per session.

Exercise

Regular moderate exercise is great for your body and your brain. Staying active during the day can help you sleep better at night by supporting your circadian rhythm’s function. Be careful not to exercise too close to bedtime though— that could prevent you from falling asleep on time.

It can be frustrating to experience poor sleep when all you want is a good night’s rest. Lifestyle changes can definitely help with circadian disruption, but it’s important to understand when you might need to take additional action. If lifestyle changes don’t improve your sleep, it’s important to consult your doctor or a sleep expert to find another solution. To find accredited sleep facilities near you, check out this tool by the American Academy of Sleep Medicine.

It’s not just our sleep that our circadian rhythms have an impact on, it’s our entire body! Our internal clocks take care of us by helping us function properly each day, so it makes sense that we need to take care of it as well.

Sweet Dreams,

Michael J. Breus, PhD, FAASM

The Sleep Doctor