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What is a Circadian Rhythm & How It Affects Sleep

What is a Circadian Rhythm & How It Affects Sleep

Written By: Emily Spring

If sleep were an orchestra, your circadian rhythm would be the conductor. By syncing itself with environmental cues like daylight, your circadian rhythm signals your body to perform essential functions and processes at the appropriate time, such as preparing your body for rest and releasing hormones that help you sleep.

Just as an orchestra would be lost without the maestro’s baton to guide them, your body is unable to maintain its proper beat nearly as well on its own.

That said, when your circadian rhythm is thrown off, your sleep schedule and physical and mental wellness may falter. In this guide, we’ll explore the circadian rhythm, its relationship to sleep, and why it's integral to your overall health.

What is Circadian Rhythm & How Does It Work?

What is circadian rhythm and how does it affect sleep? Before we take a deep dive into how your circadian rhythm helps you sleep, it’s important to discuss the important role it plays in the human body.

Circadian rhythm refers to various 24-hour cycles that are scheduled by your body’s internal clock.1 It’s the system by which your body knows when to execute several different functions and processes that affect physical, mental, and behavioral aspects of your biology. In addition to human beings, most living things are on a circadian rhythm, including:

  • Animals
  • Microbes
  • Plants

In other words, your circadian rhythm is an internal time-keeping system that helps your body decide the best time of day or night to perform essential bodily functions. Among other important processes, your circadian rhythm is essential for regulating your body’s:2

  • Blood pressure
  • Hormone production
  • Temperature

For many of these processes, timing is everything. Your body is better at performing certain functions at night when you’re asleep and others during the day. What’s your circadian rhythm? It’s the system your body uses to distinguish those times from each other.


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How Does Circadian Rhythm Affect Sleep?

One of the most important cycles that are linked to your circadian rhythm is your sleep-wake cycle. This is the schedule on which your body knows when to power down for sleep and when to re-energize when it’s time to wake up. The schedule is determined by your master clock.

Your master clock or biological clock is located in your brain, near the front of the hypothalamus in the suprachiasmatic nucleus (SCN).1 This part of the brain is extremely sensitive to changes in light, which is why circadian rhythms run on 24-hour loops. It’s also why a regular sleep/wake cycle follows a day/night schedule.

Humans are naturally diurnal creatures, meaning we tend to want to be active during the day when the sun is up and sleep at night when it’s dark. This is because your internal clock reads environmental indicators like daylight to instigate processes that are integral to falling asleep and waking up. These processes include:

  • Melatonin release – Melatonin is a hormone that’s naturally produced in the pineal gland in your brain.3 Its primary job is to help regulate your sleep schedule. When night begins to fall, your body begins releasing melatonin to help you fall asleep. As morning approaches, your brain slowly decreases melatonin release.
  • Cortisol release – In some ways, cortisol is melatonin’s foil, giving you energy and encouraging wakefulness where melatonin makes you tired. Cortisol production decreases the closer you get to bedtime and increases as morning draws near.4 
  • When it comes to getting a good night’s sleep, melatonin and cortisol regulation is crucial, which means that keeping your circadian rhythm on track so that your body knows when to release melatonin and preserve cortisol, among other functions, is also important.

    When your circadian rhythm is following the correct beat, you’re more likely to:1

    • Fall asleep faster 
    • Sleep more deeply 
    • Stay asleep longer

    What Factors Affect Your Circadian Rhythm?

    Tired but can’t sleep at night? For most people, your circadian rhythm is going to get thrown off from time to time. Sudden changes to your lifestyle, diet, or health can impact your sleep and complicate your internal clock.

    When your clock is disrupted, you can develop what’s known as a circadian rhythm sleep-wake disorder, or CRSWD. 

    There are several common types of CRSWDs.1 They include:

  • Jet lag disorder – Skipping from time zone to time zone is one of the most notorious ways of disrupting your circadian rhythm. Because your circadian rhythm is so highly influenced by light, it has trouble staying on beat when daylight signals don’t match your internal clock. This type of disruption is often experienced by people when they’re traveling, hence the name. 
  • Shift work disorder – This disorder occurs when your work schedule doesn’t match up with a day/night sleep schedule. When you work overnight, you’re forced to sleep when the sun is up, which confuses your rhythm and can prevent you from sleeping well. This disruption of the sleep-wake cycle can cause sleep problems.
  • Advanced sleep phase disorder – Approximately 1% of the population suffers from this disorder. It’s characterized by the need to go to bed earlier at night and wake up earlier the next morning. 
  • Delayed sleep phase disorder – Do you tend to stay up until the wee hours and sleep in the next day? If so, you could have delayed sleep phase disorder. This disorder pushes back bedtime by keeping you awake longer. This can also mess with your sleep pattern and make you reset your biological clock.
  • Non-24-hour sleep-wake disorder – When your body can’t read environmental cues like daylight, your circadian rhythm can fluctuate rapidly by minutes or even hours. 
  • Irregular sleep-wake rhythm disorder – In some cases, the master clock itself becomes impaired, throwing the circadian rhythm out of whack. If you find yourself sleeping at odd and inconsistent times or taking a lot of naps, you could have irregular sleep-wake rhythm disorder.
  • Depending on the specific CRSWD and the underlying conditions that cause it, these disorders can last for a few days, a few weeks, a few years, or longer. 

    How to Keep Your Circadian Rhythm

    Maintaining a proper circadian rhythm isn’t just necessary for good sleep—it’s vital for your overall health. This is because there are certain things your body does better when you’re out cold, like processing the day’s information, storing long-term memories, and engaging in cell regeneration, among other things.

    Furthermore, studies have shown a link between proper circadian rhythm and heart health, suggesting that when your internal clock is ticking properly, so is your heart.

    To that end, here are five ways you can maintain your circadian rhythm:

  • Get plenty of exercise – There’s evidence that suggests that exercise during the day can help keep your circadian rhythm modulated.5 Exercise also directly impacts your sleep-wake cycle. 
  • Spend time in the sun during the day – As mentioned, your circadian rhythm is greatly influenced by the sun. Spending time in the sunlight during the day, especially early in the morning, can help keep your circadian rhythm balanced.1
  • Be consistent about sleep – It’s important to get the recommended seven to nine hours of sleep every night. But it’s also important to go to bed at the same time every night and wake up at the same time each morning.1 
  • Facilitate deep sleep – Deep sleep, or REM, is categorized by vivid dreams and is essential to deep sleep and cognitive development. Promote more restful sleep by incorporating sleep-promoting ingredients into your day-to-day life, such as almonds, turkey, kiwi, and reishi mushrooms.
  • Limit light exposure before bed – Artificial light from lamps, blue light from screens, and other devices with bright light can disrupt your sleep schedule and your circadian rhythm. Experts suggest saying goodnight to your electronic devices at least one hour before bed because too much use can lead to sleep deprivation.6
  • Skip your afternoon nap – Afternoon naps might be one of the few things that get you through the last few hours of your work day, but they could be throwing off your circadian rhythm. If you must take a nap, be sure to keep it short and take it early in the afternoon to give your internal clock time to readjust before evening rolls in.7
  • That said, if you suffer from long-term circadian rhythm disruption, an associated sleep disorder, or a medical condition, you should consult with your healthcare provider about the best course of treatment for you. 

    Find Your Perfect Rhythm with Plant People

    What is your circadian rhythm? Your circadian rhythm is integral to regulating your body’s functions, such as your blood pressure, hormone production, and sleep cycles. A disruption in your internal clock can affect your sleep. As such, it’s critical that you support your circadian rhythm by exercising regularly, limiting light exposure come bedtime, and promote deep sleep with the proper diet.

    At Plant People, we believe in the power of nature to unlock your full potential. Our doctor-formulated, plant and mushroom supplements are designed to live your life to the fullest—even if that means spending more time in bed.

    If you’re having trouble sleeping, our NightLight Mushroom Cacao Mix is a delicious way to increase your chances of drifting off peacefully and getting a deeper, more restful sleep. Reishi mushrooms bring their powerful calming properties to relax your body and settle your mind, while magnesium helps support neurotransmitters that help you sleep. Explore our sleep supplements ranging from functional mushrooms to CBD/CBN, so you can find the right sleep solution. You can also check out our blog on how to get better deep sleep and uncover easy lifestyle changes you can make for better sleep.

    Need more sleep solutions? Take our quiz today and discover how Plant People can help you sleep and live better. 


    Written by Emily Spring 

    Emily Spring is the Director of Marketing at Plant People. A longtime proponent of balanced living, she has enjoyed over 8 years driving growth in the lifestyle, health and wellness sectors with deep experience in functional solutions for optimizing anyone's everyday life.


    Reviewed by Gabe Kennedy

     Co-Founder of Plant People, Gabe Kennedy is an acclaimed chef and entrepreneur. Growing up in a house of healers and herbalists, he is passionate about the power of food as a tool for health, and actualized this passion and belief system into his company, Plant People. Named to Forbes 30 under 30 Gabe has shaped menus and cooked his way around the world with his mission to promote a more communal, green and healthy world.

     Gabe is a graduate of The Culinary Institute of America and Cornell University School of Hotel Administration. You can learn more about his work at his website.


    1. Sleep Foundation. What Is Circadian Rhythm?
    2. Rise Science. Your Biological Clock: There’s a Right Time to Do Everything.
    3. Mayo Clinic. Melatonin.
    4. Queensland Health. 7 amazing things that happen to your body while you sleep.
    5. Acta Cardiologica Sinica. Circadian Rhythm, Exercise, and Heart.
    6. Cleveland Clinic. 3 Reasons to Ditch Your Phone Before Bed.
    7. Mayo Clinic. Napping: Do’s and don’ts for healthy adults. 

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