What exactly is a circadian rhythm?

A circadian rhythm is a daily process that occurs naturally and without outside influence. You can find these rhythms throughout nature, in plants and animals. They are vital to many organisms’ survival and exist even when there are no external stimuli present.

Circadian rhythms are the bodily and mental cycles that the body and brain follow, resulting in changes in the physical and emotional states and mood and behavioral changes. In humans, circadian rhythms are 24-hour patterns that allow for fluctuations in one’s physique and mental conditions, as well as mood and behavioral changes. For example Human Factors in Health Care Systems can help in such way too.

The sleep-wake cycleTrusted Source, or circadian rhythm, is a 24-hour pattern that most humans unconsciously follow. As a result, we generally become tired at night and more awake during daytime hours.

However, this natural human tendency to sleep and wake isn’t the only thing dictated by our circadian rhythms; they include other factors as well.

The following are some examples of circadian rhythms in humans:

  • hormonal activity
  • body temperature
  • digestion
  • immune function

How does it work?

Circadian rhythms are essential biological processes that occur without external cues. This is because the human body responds to internal biological clocks, which naturally exist in humans and their cells.

The National Institute of General Medical Sciences notes that nearly every tissue and organ contains its biological clock. These clocks result from certain proteins interacting with cells in the body, instructing them to be more active or slow down.

The master clock, known as the suprachiasmatic nucleus (SCN), controls all individual clocks in the body. This structure contains approximately 20,000 nerve cells and receives direct input from the eyes.

The SCN interprets information picked up by the eyes regarding light or darkness and tells cells how to respond accordingly. Light plays an important role in regulating this process by keeping a circadian rhythm synchronized with a 24-hour day.

How does it relate to sleep?

The body’s circadian rhythms regulate the sleep-wake cycle. They influence sleep since the body and brain react to darkness when most people feel tired and tend to nod off. The body’s biological clock instructs cells to slow down when it gets dark. Melatonin rises in the evening, allowing you to fall asleep as darkness sets in. It reaches its maximum at 2–4 A.M. before declining through the day, allowing you to get up early.

What affects circadian rhythm?

Light is the primary environmental factor that helps control the human body’s natural sleep rhythm. In addition, other elements like food and activity may help to keep this sleep cycle in sync with the Earth’s 24-hour day. But unfortunately, many things can be a barrier to this process.

What can disrupt them?

Several elements may affect your circadian rhythms throughout the day, especially if you go to bed late or get up early.

  • Light
  • Color
  • Unhealthful sleep habits
  • Shift work
  • Travel
  • Underlying conditions

How to Maintain a Healthy Circadian Rhythm

There are a few key things to remember to maintain a healthy circadian rhythm. First, try to go to bed and wake up simultaneously every day. This will help your body get used to these times and establish its rhythms around them. Some people find it helpful to set the alarm for themselves in the morning, so they are up at the same time each day. This can help the body adjust and start feeling tired when it’s time to sleep so that you wake up on time.

A regular sleep-wake schedule includes days off from work, like weekends. However, since light can disrupt circadian rhythms, being mindful of when to limit exposure is key.

People who are having difficulties sleeping may benefit from drinking some soothing herbal teas or supplements. However, before taking medications that contain active components, consult a doctor.


Our bodies experience natural cycles each day, called circadian rhythms. The most commonly known example of these rhythms is the sleep-wake cycle.

To keep a healthy circadian rhythm, we may need to change our habits to match the patterns of nature. This could help avoid some problems with sleeping or waking.

Anyone unsure about their symptoms should talk to a doctor for an accurate diagnosis and plan for management.