Circadian Rhythm

Your body has its own clock that follows a 24-hour cycle. The physical and mental changes it causes are called circadian rhythms. The study of circadian rhythms is known as chronobiology. Circadian rhythms are synced with a master clock in the brain and follow diverse systems of the body. They are linked to the day-night cycle because this master clock is directly impacted by environmental signals, particularly light. Circadian rhythms have an impact on your sleep patterns as well as other aspects of your body’s functioning, such as hormones, body temperature, and eating habits. They may create health issues if they get out of sync.

How Does Circadian Rhythm Work?

The Suprachiasmatic Nucleus (SCN), a region of your brain, has about 20,000 nerve cells that make up your “master clock.” Your circadian rhythms are controlled by this structure, which is located within the hypothalamus. The SCN is extremely sensitive to light, which acts as an important external cue in influencing the signals transmitted by the SCN to coordinate internal body clocks. As a result, circadian rhythms are intimately linked to day and night. While other factors such as exercise, social interaction, and temperature can influence the master clock, light has the greatest impact on circadian rhythms.

Also read- What happens to the brain when we are sleeping?

Circadian Rhythm in Babies

A circadian rhythm does not form in newborns until they are a few months old. This can lead them to have unpredictable sleeping habits in their initial days, weeks, and months of life. As they adjust to their surroundings and experience changes in their bodies, their circadian rhythm evolves. Melatonin is released by babies around the age of three months, and cortisol is produced between the ages of two and nine months.

Circadian Rhythm in Teens

In teenagers, melatonin levels may not begin to climb until 10 or 11 p.m., or perhaps later. As a result of this change, a teenager will need to sleep later in the morning. Their peak sleeping hours are between 3 and 7 a.m. or even later but they still require the same amount of sleep as children.

Circadian Rhythm in Adults

Melatonin releases into adults’ systems well before midnight, making them drowsy. They are most lethargic between the hours of 2 and 4 a.m. and 1 and 3 p.m. Older adults may notice that their circadian rhythm shifts as they become older, and they start going to bed earlier and waking up in the early hours of the morning.

What Is a Circadian Rhythm Sleep Disorder?

According to the American Academy of Sleep Medicine (AASM) International Classification of Sleep Disorders, a circadian rhythm sleep-wake disorder occurs because of an alteration to the body’s internal timekeeping system, the clock’s inability to entrain roughly every 24 hours, or a misalignment between the clock and a person’s external environment.

Most Common Circadian Rhythm-Related Sleep Disorders

Delayed Sleep Phase Disorder: Some folks are awake at night and can’t fall asleep until the wee hours of the morning, forcing them to sleep late into the next day.

Advanced Sleep Phase Disorder: Some people fall asleep early in the evening, from 6:00-9:00 p.m., and wake in the early hours of the morning.

Irregular sleep-wake rhythm disorder. With this disorder, people’s circadian rhythms are jumbled. They may sleep in a series of naps over 24 hours.

Jet lag, or rapid time zone change syndrome. This involves symptoms like too much sleepiness and a lack of daytime alertness in people who travel across time zones.

Shift work sleep disorder. This sleep disorder affects people who often rotate shifts or work at night.

Causes of Circadian Rhythm-Related Sleep Disorders

  1. Lifestyle Change: People who change their exposure to daylight, shift the timing of their daily activities, and strategically schedule naps may be able to manage better with some circadian rhythm sleep disorders.
  2. Bright light therapy: This therapy synchronizes the biological clock by exposing the eyes to low-intensity, bright light for short periods of time at specific times of day.
  3. Sleep hygiene: These guidelines assist patients in developing healthy sleeping patterns.
  4. Medications: To encourage sleep, a hypnotic may be taken, whereas to stimulate wakefulness, a stimulant may be prescribed.
  5. Melatonin: Some circadian rhythm sleep problems may be alleviated by taking melatonin at specific times and amounts.

References and Further Reading-

  1. https://my.clevelandclinic.org/health/diseases/12115-circadian-rhythm-disorders
  2. https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx
  3. https://www.sleepfoundation.org/circadian-rhythm
  4. https://www.thensf.org/what-is-a-circadian-rhythm/
  5. https://www.healthline.com/health/circadian-rhythm-sleep-disorder#outlook
  6. https://aasm.org/resources/factsheets/crsd.pdf