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Know All About the Circadian Rhythm

Written By HealthKart
Medically Reviewed By Dr. Aarti Nehra

Circadian Rhythm

Circadian rhythm refers to the natural sleep-wake pattern that affects the mental, behavioural, and physical alterations that happen in our bodies. As per the National Institute of General Medical Science, this rhythm runs a cycle of twenty-four-hour, generally, as a response to light and darkness. Our internal body or biological clocks are actually the natural timing equipment of our cells. They are a set of molecules, which instruct our cells (like when to release the hormone that makes us feel awake, sleepy, or hungry) so that the circadian rhythm of our body stays on track.

In our body, one bunch of molecules helps to activate other molecules’ production – this helps trigger or activate the next stage in the cycle while enabling cells to track time. Our body has one main biological clock as well. This clock is located above the optic nerve in our brain or the hypothalamus. It is also known as the suprachiasmatic nucleus. It is sometimes called the circadian clock.

The circadian clock grasps its cues from the darkness and light that we are exposed to ( as these cells are located near our eyes, they receive any changes directly from our eyes). And the circadian clock of our body cooperates with the other clocks of our body by controlling things like hormone levels and body temperature that respond by activating each cell’s respective molecular clocks. 

Understanding Circadian Rhythm Disorder

Most bodies follow the same schedule (like feeling sleepy) as we are exposed to the same patterns of light throughout the day. Although, it comes in variation due to our behavioural changes or genetic makeup.

Circadian rhythm disorder is an issue that happens when the internal clock of our body, which tells us when to wake or when to sleep, is not correctly synced with our environment. People with circadian rhythm sleep disorders often feel difficulty in falling asleep or wake up too fast, then fail to go back to sleep. Basically, the natural sleeping and waking schedule of an individual gets disrupted when anyone goes through this condition.

What Disrupts Our Circadian Rhythm?

While circadian rhythm happens naturally, various factors might impact it throughout the day:

1. Light

Our circadian rhythm or internal clock gets easily disturbed by erratically timed light. Our circadian rhythm becomes extremely sensitive around two hours before our normal bedtime. Working under a bright light at this time could change the timing of our urge to sleep, thus we might feel sleepy and fall asleep very late at night and wake from our sleep around the afternoon. 

Sleeping in a room that is too bright might also end up waking someone earlier than usual, disturbing their sleep schedule.

2. Colour

The light colours can also disturb our circadian rhythm. Working under the white and blue lights two hours before our bedtime can also disrupt our natural sleep schedule. It could make it impossible for us to stay or fall asleep. This also happens due to the constant use of electronic devices such as computers, televisions, and phones especially before bed time. Other colours of light have less impact on our circadian clock.

3. Bad Sleep Habits

Having a bad sleep schedule might interfere with our natural circadian clock. This might include symptoms like:

  • Falling asleep very late and getting up early
  • Not having a proper sleep time
  • Drinking and eating very late at night
  • Consuming caffeine at night
  • Surfing through internet on phone or laptop at night
  • Doing mind-stimulating things at night
  • Feeling discomfort or pain in the bed

4. Work Timings

People who generally work at night shift or throughout the day might experience difficulty in their circadian rhythm

5. Travel

Those who travel very often might experience difficulty in sleeping, especially if one travels from one time zone to the other quite often. This is also called jet lag, a sense of feeling tired as our body tries to cooperate with frequently changing sleep schedules.

Maintaining a Healthy Circadian Rhythm Cycle

Numerous significant factors need to be followed to maintain healthy circadian rhythm hormones.

One should fall asleep and wake up around the same time every day. Maintaining a fixed schedule can help the body set the circadian rhythms around the same time. A lot of us prefer setting alarms to wake up every day, at the same time. This might help our body cooperate and trigger exhaustion initially, when it needs to sleep and is compelled to wake up early. But gradually we can get used to this new schedule.

This regular sleeping schedule also involves the days when there is no work like the weekends. It is also extremely crucial to choose the right light to work under at night. 

Two hours before we fall asleep is the most sensitive time. If we avoid working under blue light around this time, then it might contribute to a healthy circadian rhythm. This is why you should limit the use of electronic devices at this time. 

Other tips that might help in promoting a healthy circadian rhythm

  • Roaming outside in the morning or in bright light during the daytime 
  • Avoiding the consumption of caffeine late at night 
  •  Avoiding long napping in the late afternoon 
  • Having small meals at dinner
  • Doing calming activities like reading before sleeping

You may also want to take melatonin supplements in order to improve your sleep-wake cycle.


Circadian rhythm is a natural cycle that our bodies go through every day. The pattern of our sleep & wakefulness are examples of circadian rhythms. It is important to know the reasons behind a disturbed circadian rhythm cycle and take appropriate measures to improve the same. 

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