Everything You Need to Know About Circadian Rhythms and How They Affect Sleep

Changes in both body and mind occur at regular intervals throughout the day, known as circadian rhythms. The 24-hour circadian rhythm plays a significant role in keeping us awake and attentive throughout the day and preparing us for sleep at night. It affects our metabolism, hormonal balance, and even how hot or cold we feel.

Our internal biological clock, or circadian rhythm, may disconnect from our daily routine and external conditions. Understanding your sleep-wake cycle and the factors interrupting your circadian rhythm might help you receive the rest you need. We also discuss methods for establishing and keeping a regular sleep-wake schedule.

Circadian Rhythms: What Do They Mean?

The body's internal clock, or circadian rhythms, are periodic 24-hour cycles that operate automatically to maintain vital bodily activities. The sleep-wake cycle is perhaps the most prominent circadian rhythm.

The brain acts as a master clock that ensures all of the body's systems keep time with one another through circadian rhythms. Circadian rhythms are linked to the day/night cycle because environmental signals, particularly light, directly impact this master clock.

The Circadian Rhythm and Sleep: What Role Does It Play?

The sleep-wake cycle has a significant role in determining a person's typical sleeping habits. How alert or tired you feel it depends on a complex series of brain processes.

The brain houses the body's internal clock. The suprachiasmatic nucleus is the name given to this brain region (SCN). The SCN is an environmental light and is found near the eyes. Circadian rhythms, such as the sleep-wake cycle, are regulated by the internal clock in reaction to daytime light and nocturnal darkness.

The SCN is light-sensitive and keeps us awake and attentive throughout the day. Throughout the night, the opposite is true. When ambient light levels decrease, the SCN signals the brain to create the sleep hormone melatonin.

While light is the major signal that impacts the sleep-wake cycle, other variables, such as how long you have been up, may also play a role.

What Threatens to Derail Them?

Circadian rhythms occur independently, although they may be influenced by several things at different times of the day.


The light turned on at the wrong time may interrupt a person's circadian cycle.

According to the CDC (Centers for Disease Control and Prevention), a person's circadian clock is most receptive two hours before sleep. The use of bright lights at this time might cause a person to feel tired, leading to a later bedtime and rise times.

On the other hand, early morning light may cause a change in sleep timing. If you sleep in a light environment, you could wake up sooner than normal.


It indicates that circadian rhythms are disturbed by light colour. Blue light has the greatest effect, according to the CDC.

Exposure to blue and white lights at potentially sleep-disruptive times of day, such as two hours before bed, is recommended. Screens on electronic devices like phones, laptops, and TVs are a common source of electromagnetic radiation.

Poor Sleeping Habits

Poor sleeping habits may throw off the circadian clock. Examples of such concerns may be −

  • Sleepless nights spent partying

  • not having a regular bedtime

  • Having a meal and a few drinks after hours

  • caffeine use in the wee hours

  • Using technology past bedtime

  • engaging in intellectually

  • interesting pursuits late at night
  • having trouble getting comfortable in bed

Work in Shifts

Some people's natural circadian rhythms might be thrown off by working late hours or overnight. Shift employment disrupts people's circadian rhythms, set by the body's response to the sun's natural light and dark cycles.


Sleep and circadian rhythm abnormalities are common among frequent travelers, particularly those who often cross time zones. The term "jet lag" describes the drowsy state as a person's body adjusts to a new time zone and schedule.

The Best Practices for Keeping a Regular Sleep-wake Cycle

While trying to keep a healthy circadian rhythm, it's crucial to consider several elements.

Maintain a regular sleep-wake schedule if at all feasible. A consistent schedule might help the body adjust to the changes in its internal clock. Some people find it helpful to set the alarm simultaneously each morning. This might help the body readjust and make it easier to fall asleep at night when sleep is required.

This timetable for sleeping and waking includes non-working days as well as weekends.

Careful timing is required as exposure to light may throw off circadian cycles. According to the CDC, the two hours before bedtime are the most significant.


The body follows a daily cycle known as the circadian rhythm. The most well-known example of such a rhythm is the cycle of sleep and waking. Some sleep and wakefulness problems may be avoided by altering one's routine such that it more closely follows the natural cycles of the world around them. See a doctor for a proper diagnosis and treatment plan if you have doubts about your symptoms.

Updated on: 20-Apr-2023


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