Your circadian rhythm is your body’s internal clock. Light, sleep patterns, hormones, meals, and temperature can all influence your circadian rhythm, which in turn can influence your overall health.

Your circadian rhythm is your sleep-wake pattern over the course of a 24-hour day. It affects several systems in your body, and several factors can influence it.

Some people may experience disruptions to their circadian rhythm because of external factors or sleep disorders. Maintaining healthy habits can help you better respond to your body’s natural rhythm.

Your circadian rhythm is one of four biological rhythms in the body. It helps control your daily schedule for sleep and wakefulness. Most living things have one.

Your circadian rhythm affects several systems in your body, including digestion, temperature regulation, and hormone release.

While your brain sets your circadian rhythm, external factors can also influence it.

In the hypothalamus of your brain is a “master clock” that helps determine your circadian rhythm. This part of the brain is known as the suprachiasmatic nucleus (SCN). The SCN sends signals to other parts of your body, but it also takes in information.

The primary driver of the SCN is light. Cells in the retina of your eyes capture changes in light and dark in the environment and then send signals to the SCN. The SCN then activates certain hormones, alters your body temperature, and regulates your metabolism to keep you alert or draw you to sleep.

Although light and dark have the most significant influence on your SCN, other factors can also affect your circadian rhythm, such asTrusted Source:

  • food intake and metabolism
  • stress
  • physical activity
  • social environment
  • temperature
  • age

Hormones play a role

Hormones like melatonin and cortisol may increase or decrease as part of your circadian rhythm. Melatonin is a hormone that makes you sleepy, and your body releases more of it at night and suppresses it during the day. Cortisol can make you more alert, and your body produces more of it in the morning.

Other hormones that play a role in alertness and circadian rhythm include:

  • vasopressin
  • acetylcholine
  • insulin
  • leptin

Newborns do not develop a circadian rhythm until they’re a few months oldTrusted Source. This can cause their sleeping patterns to be erratic in the first days, weeks, and months of their lives.

Their circadian rhythm develops as they adapt to the environment and experience changes to their bodies. Babies begin to release melatonin when they are about 3 months oldTrusted Source, and the hormone cortisol develops from 2 months to 9 months old.

Once their circadian rhythm and body functions mature, toddlers and children have a fairly regulated sleep schedule. School-aged children need about 9 to 12 hoursTrusted Source of sleep a night.

Teenagers experience a shift in their circadian rhythm known as sleep phase delay. Unlike in their childhood years, with early bedtimes around 8 or 9 p.m., teenagers may not get tired until much later.

Melatonin may not rise until several hours later — closer to midnight in some cases. That shift also causes teenagers to sleep later in the morning since they still need almost as much sleepTrusted Source as children.

Adults should have a fairly consistent circadian rhythm if they practice healthy habits. Their bedtimes and wake times should remain stable if they follow a fairly regular schedule and aim for 7 to 9 hoursTrusted Source of sleep every night.

Adults likely get sleepy well before midnight as melatonin releases into their bodies. Adults also often experience a post-lunch dip around 2 to 4 p.m., during which they may feel more sleepy and less alert.

Older adults may notice their circadian rhythm changes with age. They may begin to go to bed earlierTrusted Source than they used to and wake in the wee hours of the morning. In general, this is a typical part of aging.

Sometimes, it’s not possible to follow your circadian rhythm, and your lifestyle needs and internal clock clash. This can occur because of:

  • overnight or off-hours work shifts that go against the natural light and dark times of day
  • work shifts with erratic hours
  • travel that spans the course of one or more different time zones
  • a lifestyle that encourages late-night hours or early wake times
  • medications
  • stress
  • mental health conditions
  • health conditions like brain damage, dementia, head injuries, or blindness

Certain sleep habits may also affect your circadian rhythm, such as:

How are circadian rhythms related to jet lag?

Jet lag occurs when you travel over several time zones quickly, and your body is not aligned to the time of your new environment. Your circadian rhythm is attuned to the place where you left, and it has to readjust. This may result in feeling tired during the day or feeling wide awake at night.

You may experience other changes that affect your well-being until your circadian rhythm normalizes again. It may take a day or up to a week to feel acclimated to the new time zone. It typically takes a day for each hour you shift to regulate your sleep-wake cycle.

You may even experience mild symptoms of jet lag when clocks fall backward or forward for daylight saving time. The disruption may not last too long, but your body may need a few days to adjust.

You may experience disruptions to your circadian rhythm, but you can get it back on track. Here are some tips for promoting a healthy 24-hour schedule:

  • Try to adhere to a routine each day.
  • Spend time outdoors when it’s light outside to boost your wakefulness.
  • Get enough daily exercise. Experts recommend 30 minutes three to six days a week, but even 10 minutes a day can improve sleep quality.
  • Sleep in an environment that promotes rest with proper lighting, a comfortable temperature, and a supportive mattress.
  • Avoid alcohol, caffeine, and nicotine in the evenings.
  • Power down your screens well before bedtime, and try engaging in an activity like reading a book or meditating.
  • Avoid napping late in the afternoon or evening.

Sometimes, alterations to your circadian rhythm may signal a more serious condition like a circadian rhythm sleep disorder. Examples includeTrusted Source:

  • Delayed sleep-wake phase disorder (DSWPD): With DSWPD, you awaken 2 hours or more after most people. You may think of yourself as a “night owl.” Teenagers and young adults are more prone to this condition.
  • Advanced sleep-wake phase disorder (ASWPD): People with ASWPD fall asleep a few hours before most people and then awaken very early in the morning.
  • Irregular sleep-wake phase disorder (ISWPD): Doctors diagnose ISWPD when there’s no clear circadian rhythm pattern.
  • Non-24 sleep-wake rhythm disorder (N24SWD): N24SWD occurs when your circadian rhythm is out of sync with a 24-hour day. This mostly occurs in blind people.
  • Shift work disorder: An off-hours job or a job with unpredictable hours may cause you to develop shift work disorder.
  • Jet lag disorder: You get jet lag from traveling over several time zones quickly.

Symptoms related to these conditions include:

  • difficulty falling asleep at night
  • insomnia
  • sleep loss
  • waking frequently throughout the night
  • waking and not being able to go back to sleep in the middle of the night
  • problems waking in the morning
  • tiredness throughout the day
  • depression or stress

Treating these conditions may include a variety of approaches. You may try to:

Maintaining your circadian rhythm is vital to your health. Disruption can affect several different organ and body systems, includingTrusted Source your:

  • cardiovascular system (heart and blood vessels)
  • endocrine system (hormones)
  • gastrointestinal system (digestion)
  • immune system
  • renal system (urination)
  • reproductive system
  • skeletal system (bones)

Short-term disruptions to your circadian rhythm may result in:

  • memory issues
  • lack of energy
  • delayed wound healing
  • changes to your hormone cycle that may impact fertility
  • problems with your digestion and bowels
  • shifts in your body temperature

Long-term disruptions to your circadian rhythm may make you more susceptible to diabetes, obesity, and mental health conditions.

If you experience one of these issues for a prolonged period, consider making a doctor’s appointment:

  • have trouble getting enough sleep every night
  • cannot fall asleep easily
  • awaken several times a night and fail to get quality sleep
  • have trouble waking up
  • feel extremely tired during waking hours

Your circadian rhythm is your body’s natural way of keeping to its 24-hour body clock, helping your body operate on a healthy sleep-wake schedule. A healthy, active lifestyle that promotes proper rest will help you maintain this important function.

See a doctor if you experience prolonged difficulties sleeping or extreme fatigue during the day to find out how you can realign with your circadian rhythm and get proper rest.