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What is Circadian Rhythm

What is Circadian Rhythm

Did you know that your body has a clock of its own? However, you'll never hear it tick. That biological clock is capable of causing mental and physical changes commonly known as circadian rhythms. Some of the changes circadian rhythms can cause in your body are eating habits and body temperature. 

Your circadian rhythms help control your daily schedule for sleep and wakefulness. If you want to find out about this biological element responsible for your sleep patterns, then continue reading.

How Do Circadian Rhythms work? 

The suprachiasmatic nucleus is a vital part of the brain consisting of approximately 20,000 nerve cells that makes up the master clock of your body. The structure is located within the hypothalamus, and it's the one responsible for circadian rhythms.

While internal factors such as genes and other natural activities in your body affect these circadian rhythms, the external environment can also influence and alter them. For example —light; your body is biologically hardwired to sleep whenever it's dark and stay awake in the presence of light. 

Note that your body's master clock directly links to your eyes' nerves. That means your eyes will signal your brain to produce melatonin (a hormone responsible for making you sleepy) when it's dark outside.  At sunrise, your eyes will also signal the brain to reduce melatonin secretion.

Disrupted Circadian Rhythm

The occurrence of circadian rhythms is natural. However, some factors may result in a disrupted circadian rhythm, they are; 


Those who travel frequently are also likely to experience disruptions in their circadian clocks and sleep. It usually happens especially when shifting time zones, a situation known as jetlag. Generally, Jetlag is when you feel tired or groggy due to changes in time zones as your body tries to catch up with new rhythms of a day.

Shift Work

Suppose you work outside the conventional 9-5 period; you're most likely to suffer from a shift work disorder. Essentially, you'll experience disruptions in your circadian rhythm. Notably, shift work will change your rhythms as your body responds to the light and dark cycles of the sun. 


One notable cause of disrupted circadian rhythm is irregular timed light. According to CDC (Center for disease control and prevention), your circadian clock is highly sensitive 2 hours before you fall asleep during your usual bedtime. During this period, if you use bright lights, it will shift your need to fall asleep later than usual, which may result in waking up late in the morning.  

Unhealthy Sleep Habits 

Unhealthy sleep habits can also disrupt your circadian clocks, bringing about issues like;

  • Late-night consumption of coffee 
  • Falling asleep late and waking up earlier
  • Late Night use of electronic devices like mobile phones, tablets, etc. 
  • Having no specific sleep time
  • Eating very late at night 
  • Engaging in late-night activities that stimulate the brain

Aside from disrupting your body's clock, you may also experience symptoms of jet lag, especially if you sleep very late.


According to the CDC, light is a potential disruptor of circadian patterns, with blue light being the strongest. Both white and blue light will make it difficult to fall asleep 2 hours before your usual bedtime. Sources of these lights are electronic screen devices like; televisions, computers, phones, etc. Other light wavelengths have a lesser impact on your circadian clock. 

Different People with Different Sleep Patterns

If you've noticed, there are certain periods across the day when you feel more active and other times when you feel low on energy. That is your personal circadian rhythm or chronotype at work. Though it mostly run in families, it varies from individual to individual. People generally fall into either of the two groups outlined below; 

Night Owls

According to some researchers, your biological clock runs slower than 24 hours if you're an evening person, i.e., a night owl. That means you'll experience difficulty waking up and staying active in the morning, but you'll feel more energetic late in the day, say around 10.00 pm. 

Also, as you age, your circadian clock naturally changes–for example, most teens prefer retiring to bed late at night and sleeping more than younger children. On the other hand, your job or school work may require you to shift your schedule from being a night owl to a morning person. The good news is you can alter your circadian clock if you want but gradually, as you'll later see. 

Early Birds

If you feel you're more energized when you wake up in the morning and also find it easy waking up during this period, chances are; you're a lark, i.e., a morning person. Unlike the night owls, some research indicates that the body clock of early birds runs a bit faster than 24 hours. 

Related Content: How much sleep should you get?

How to Reset your Circadian Rhythm

Though you may experience disruptions in the circadian clock, you can get it back on track yourself. Below are tips that'll assist in resetting your circadian rhythm; 

  • Exercise regularly for about 20 minutes daily 
  • Sleep in a room with a comfortable temperature and proper lighting with a supportive mattress. 
  • Try sticking to your regular daily routines
  • Avoid taking naps in late evenings or afternoon and try napping around midday
  • Avoid consuming alcohol or coffee late in the evenings.
  • Boost your wakefulness by spending more time outdoors when it's light. 
  • Turn off all your electronic screen devices 2 hours before retiring to bed, then try meditating or reading a book. 

Circadian Rhythm Sleep Disorders 

If you find yourself waking up earlier than usual, during a sleep cycle, or having any difficulties falling asleep whatsoever, chances are; that circadian rhythm sleep disorders might be the cause. 

The good thing is that there are treatment options, e.g., sleep medicine for these disorders, that a sleep specialist can recommend. Common types of circadian rhythm disorders are; 

Advanced Sleep Phase Disorder

If you tend to fall asleep early in the evening between 6.00 pm and 9.00 pm and wake up between 2.00 am and 5.00 am, then you might be suffering from this sleep disorder. Features associated with this disorder include; 

  • It affects older adults and middle-aged individuals

  • It might run in families 

  • You may complain of waking early in the morning or insomnia and feeling sleepy during early evenings or late afternoons.

Jet lag

As mentioned earlier, you'll experience jet lag if you travel between two or more different time zones. So, the disruption of the sleep-wake cycle makes it challenging to adjust and even function in a different time zone. 

Generally, delaying sleep is easier than advancing it; suppose you're traveling westwards than eastwards. Features associated with jet lag include;

  • General fatigue

  • Changes in appetite

  • Mood disturbances or feeling discomfort 

  • Alteration in the gastrointestinal functions

Irregular Sleep-Wake Rhythm

This sleep disorder is commonly associated with undefined sleep-wake cycles. Essentially, you might find yourself taking more naps than usual in a 24-hour cycle. Common Symptoms of this circadian rhythm sleep disorder are; sleeping excessively and chronic Insomnia. 

People with this disorder usually have neurological conditions such as dementia, individuals with traumatic brain injuries, and intellectually disabled children, among others.

Delayed Sleep Phase Disorder

If you're waking up 2 hours later than a normal sleep cycle, then it might be courtesy of this sleep disorder. For example—you're a night owl who falls asleep at midnight or later and sleep in up to 1.00 pm. Features of this sleep disorder are; 

  • It might run in families

  • You may be considered lazy and poor at executing your normal morning responsibilities. 

  • You're more active and productive at night.

  • Commonly affects young adults and adolescents

  • Feeling sleepy during the day, suppose you're forced to wake up early in the morning. 

When Do you Need to See a Doctor?

Treatment options and sleep medicine are meant to help adjust the patients' sleep patterns to get necessary normal sleep function. Some of these treatments are; hypnotherapy (bright light therapy) and behavioral therapy to adjust bedtime. 

Note that bright light therapy is meant to reset the circadian rhythm of a patient to the desired pattern. In case you feel like your circadian rhythms are off or disruptions with your sleep cycle, it's crucial you speak to your doctor or a sleep specialist. 

Sleep deprivation or poor sleep quality can cause the following health complications;

  • Sleep apnea

  • Obesity

  • Heart attack

  • Anxiety and depression

  • Psychosis

  • Diabetes 

  • Hypertension

It'll be helpful to inquire from a health professional about ways of limiting circadian disruptions. Also, you can use a Melatonin supplement to reset your circadian rhythms but use it under sleep specialist instructions. 

Final Thoughts 

Circadian rhythm plays a vital role in ensuring your body runs on a healthy sleep-wake cycle. Also, living a healthier lifestyle and engaging in activities that promote proper and healthier sleep patterns will go a long way to maintaining the proper functionality of your body as a whole. If you are experiencing prolonged sleep difficulties or general fatigue, consider seeing a sleep specialist or a qualified doctor and know how you can realign your circadian rhythm to sleep properly. 

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