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Circadian Rhythm: What It Is, How It Works And Importance

Published: Jun 05, 2024
Updated: Sep 13, 2024
Circadian Rhythm: What It Is, How It Works And Importance
In this article
    Reading time
    9 min

    It is important for us, as humans, to get a good amount of sleep each night to function properly. We are able to sleep and wake each time because of our body’s internal clock, also known as circadian rhythm.

    But, what exactly is it and how does it work to regulate our sleep-wake cycle, body temperature, and much more? In this article, we will discuss it in more detail.

    Key Takeaways
    Circadian rhythm is our body’s internal clock. It is located in our brain.
    Circadian rhythm is important to help us determine when to sleep and when to be awake.
    Disruptions of the body clock can lead to sleep disorders.
    Some health implications can include poor sleep quality, mood changes, increased risk of health conditions such as hypertension and diabetes.
    You can fix your sleep schedule by following sleep hygiene tips such as having a consistent sleep schedule, avoiding caffeine at night, limit blue light exposure and getting more sunlight.

    What Is Circadian Rhythm?

    Circadian rhythm can be defined as the 24-hour internal clock that is located in our brain [1]. It is located within a tiny cluster of cells called the suprachiasmatic nucleus (SCN). It controls when we feel alert or sleepy based on the light-dark cycle or light changes in the environment. It also sends a signal to produce melatonin so that we can fall asleep at night.

    The circadian clock helps us to adapt to any changes in our surroundings and respond appropriately to any changes in temperature, eating habits, and digestion.

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    How Does The Circadian Rhythm Work?

    The way that the circadian rhythm works starts from the suprachiasmatic nucleus (SCN) in the brain. As the body follows the light and dark hours, it will send signals to one of the brain pathways.

    During the light cycle, your eyes captures changes in the environment. From there, it sends signals to various cells in the brain such that it does not release melatonin. At night, it does the same with the only exception being melatonin production. Melatonin is produced as the brain registers that it is night and it is time to sleep [1].

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    Importance of Circadian Rhythm

    To simply put, the circadian rhythm is important because it affects sleep. When it falls out of sync so will our sleep. Without proper signals sent to our brain, our body will not know when it should be asleep or awake.

    Causes of Disruption

    In the past, humans were exposed to minimal light at night. However, with technological advancements, it introduced new sources of light. The most common light source that leads to disrupted circadian rhythms are electronic devices. This is due to excessive blue light emission.

    Besides this, some other causes include:

    • Social Jet Lag: Social pressures (e.g. school and work) that results in delaying sleep throughout the week.
    • Shiftwork: These non-traditional sleep schedules are often unpredictable which results in a shift in circadian rhythm patterns.

    Signs of a Disrupted Circadian Rhythm

    Here are some common signs and symptoms:

    • Difficulty falling asleep or waking up: You may experience problems with going to bed or waking up in the morning.
    • Irregular sleep patterns: Poor sleep habits such as going to sleep only in the middle of the night and waking up later. Having an inconsistent sleep schedule.
    • Daytime sleepiness: You may feel extremely tired during the day and in need of a nap despite having slept at night.
    • Digestive issues: Irregular appetite or indigestion, disrupting normal eating patterns.
    • Poor physical performance: Reduced energy levels or poor coordination when it comes to daily routine or work.
    signs of a disrupted Circadian Rhythm
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    Understanding Circadian Rhythm Sleep Disorders

    If you find that you are unable to fall asleep, slept poorly or are not able to go back to sleep after waking, it may be a sign of circadian rhythm disorder.

    Circadian rhythm disorders are disruptions to a person’s circadian rhythm. These are the most common circadian rhythm sleep disorders:

    • Jet Lag: This happens when you are flying between two or more time zones, causing a shift in circadian rhythm.
    • Delayed Sleep Phase Syndrome: This happens when a person is alert even at night and only able to fall asleep in the middle of the night.
    • Advanced Sleep Phase Disorder: This usually happens to older adults. It is when a person is able to sleep in the early evening but wakes up in the early morning as well.
    • Shift Work Sleep Disorder: This usually happens to shift workers especially those on night shifts. A shift worker often feels ongoing sleepiness.

    Health Implications

    As our circadian clocks are disrupted, it can affect the sleep cycle. This, in turn, affects our health. Some of the health implications include:

    • Poor sleep quality
    • Mood changes
    • Increased anxiety and depression
    • Increased risk of metabolic syndrome (hypertension, diabetes, coronary heart diseases, etc.)
    • Diminished quality of life
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    Benefits of Regulating Circadian Rhythm

    Since we know that a disrupted circadian rhythm can lead to various health implications, it is best to regulate and maintain a healthy circadian rhythm.

    According to studies, there is a possible correlation between a healthy circadian rhythm and our physical, mental and emotional well-being.

    Some of the benefits of regulating your circadian rhythm:

    • Improved sleep quality
    • Reduced risk of chronic diseases
    • Improved cognitive function
    • Improved social interactions
    • Higher energy levels

    Tips for Maintaining a Healthy Circadian Rhythm

    Tips for maintaining a healthy circadian rhythm 
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    To ensure that your sleep-wake cycle is synchronized with your circadian rhythm, you should practice good sleep hygiene. Here are a list of tips to help you get started:

    1. Have a consistent sleep schedule: Ideally, you should aim to go to bed and wake up at the same time each day, even on weekends. You may use a circadian rhythm calculator to determine the timings. Alternatively, you may also try using the smart alarm clock feature in ShutEye® app.
    2. Exposure to natural light: As much as possible, try to spend your time outdoors during the daytime. Natural lighting can help to regulate your body’s internal clock.
    3. Limit blue light exposure: Make it a part of your bedtime routine to limit unnecessary blue light exposure. Switch off your electronic devices about 30 minute to 1 hour before bed to avoid melatonin disruption.
    4. Exercise regularly: Exercising regularly can help with your sleep-wake cycle.
    5. Avoid caffeine and heavy meals before bedtime: These can be triggers for insomnia or indigestion which can keep you up at night. Thus, disrupting sleep.

    How To Reset Your Circadian Rhythm

    Having trouble falling asleep and dealing with daytime sleepiness can be frustrating. Fortunately, there are ways to reset and fix your sleep schedule.

    1. Bright Light Therapy: Consider trying light therapy as an approach. Controlling your light exposure can alter melatonin production and shift your sleep and wake times either earlier or later.
    2. Melatonin Supplements: In some cases, you may choose to opt for melatonin supplements to induce sleep faster. This works especially for those with jet lag.
    3. Adjusting your sleep schedule: Make gradual adjustments to your sleep schedule so that your body can slowly adapt to new changes.
    4. Medications: If necessary, you may choose to take medications to induce sleep or help with wakefulness. However, they may have side effects so it is best to always consult with a doctor prior to trying any new treatment.

    Conclusion

    The fact is that sleep is important for our health. Our biological clocks plays an important role in maintaining healthy sleep cycles. Without this, the way that our body functions would be impacted. So, let us work our way towards getting better sleep each night!

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    FAQ

    The circadian rhythm is our body's internal clock that operatures according to the 24-hour cycle.

    You will know that your circadian rhythm is disrupted when you notice signs and symptoms such as difficulty falling asleep or waking up, irregular sleep patterns, daytime sleepiness and reduced cognitive function.

    You may reset your circadian rhythm by following a few strategies such as melatonin supplement, adjusting your sleep schedule or trying bright light therapy.

    The best time to sleep would vary according to individual preferences and lifestyle. Generally for adults, you should aim to go to bed between 10pm to 12am at night.
    About authors
    Dr. Cui is a board-certified internal medicine physician and applied psychologist with more than 30 years of experience in both fields especially in terms of the regulation and intervention of sleep disorders.
    Dr. Julian Lim is regarded internationally as an expert in mindfulness and sleep, with over 40 peer-reviewed publications and a position on the editorial board of the scientific journal Mindfulness. He is currently an Adjunct Professor at the Centre for Sleep and Cognition at the National University of Singapore.

    Davis, L. K., Bumgarner, J. R., Nelson, R. J., & Fonken, L. K. (2023). Health Effects of Disrupted Circadian Rhythms by Artificial Light at Night. Policy Insights from the Behavioral and Brain Sciences, 10(2), 229-236. https://doi.org/10.1177/23727322231193967

    National Institute of General Medicine (2023) Circadian Rhythms [online]. https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms

    Reddy S, Reddy V, Sharma S. Physiology, Circadian Rhythm. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519507/

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