Your circadian rhythm helps control your daily schedule for sleep and wakefulness. This rhythm is tied to your 24-hour body clock, and most living things have one. Your circadian rhythm is influenced by outside things like light and dark, as well as other factors. Your brain receives signals based on your environment and activates certain hormones, alters your body temperature, and regulates your metabolism to keep you alert or draw you to sleep.
Some may experience disruptions to their circadian rhythm because of external factors or sleep disorders. Maintaining healthy habits can help you respond better to this natural rhythm of your body.
There are several components that make up your body’s circadian rhythm. It is one of four biological rhythms in the body.
Cells in your body
First, cells in your brain respond to light and dark. Your eyes capture such changes in the environment and then send signals to different cells about when it’s time to be sleepy or awake.
Those cells then send more signals to other parts of the brain that activate other functions that make you more tired or alert.
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.
Body temperature and metabolism are also part of your circadian rhythm. Your temperature drops when you sleep and rises during awake hours. Additionally, your metabolism works at different rates throughout the day.
Other factors may also influence your circadian rhythm. Your rhythm may adjust based on your work hours, physical activity, and additional habits or lifestyle choices.
Age is another factor that influences your circadian rhythm. Infants, teens, and adults all experience circadian rhythms differently.
Newborns do not have a circadian rhythm developed until they are a few months old. This can cause their sleeping patterns to be erratic in the first days, weeks, and months of their lives. Their
Toddlers and children have a fairly regulated sleep schedule once their circadian rhythm and corresponding body functions mature. Children need about 9 or 10 hours 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 in the night.
Melatonin may not rise until closer to 10 or 11 p.m. or even later. That shift also results in a teenager’s need to sleep later in the morning. Their peak sleepy hours at night are from 3 a.m. to 7 a.m. — or may even be later — but they still need the same amount of sleep as children.
Adults should have a pretty 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 seven to nine hours of sleep every night. Adults likely get sleepy well before midnight, as melatonin releases into their bodies. They reach their most tired phases of the day from 2 to 4 a.m. and 1 to 3 p.m.
Older adults may notice their circadian rhythm changes with age, and they begin to go to bed earlier than they used to and wake in the wee hours of the morning. In general, this is a normal part of aging.
Sometimes it is 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 you take.
- Mental health conditions.
- Health conditions like brain damage, dementia, head injuries, or blindness.
- Poor sleep habits, including lacking a sleep schedule, eating, or drinking late at night, watching screens too close to bedtime, or not having a comfortable sleeping space.
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 — twenty or more minutes of aerobic exercise is generally recommended.
- 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 something analog, such as reading a book or meditating.
- Do not nap late in the afternoon or evening.
Sometimes alterations to your circadian rhythm may be the sign of a more serious condition like a circadian rhythm sleep disorder. Two of these disorders are advanced sleep phase and delayed sleep phase. You may be more susceptible to these if you work an irregular shift, are blind, or are a teenager or older adult.
Delayed sleep phase disorder occurs when you go to bed and awaken two 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 phase disorder is the opposite of delayed sleep phase disorder. You actually fall asleep a few hours before most people and then awaken very early in the morning.
Disorders related to your circadian rhythm may result in having difficulty falling asleep at night, waking frequently throughout the night, and waking and not being able to go back to sleep in the middle of the night.
Symptoms related to these conditions include:
Other conditions that are tied into your circadian rhythm include:
- jet lag, caused from traveling over several time zones quickly
- shift work disorder, caused by an off-hours job or a job with unpredictable hours
- irregular sleep-wake disorder, caused by an inability to set a regular sleep and wake schedule
Treating these conditions may include a variety of approaches. You may try to:
- set a more regular schedule
- use light therapy
- take medications or supplements like melatonin to fall asleep more easily
- try an intentional shift in your sleep implemented over several days or weeks
Maintaining your circadian rhythm is vital to your health. If you experience a disruption to your circadian rhythm and struggle to get the proper amount of sleep, you may experience both short-term and long-term consequences to your health.
Disruption to your circadian rhythm can cause health conditions in several parts of the body in the long term. This includes your:
- cardiovascular system
- gastrointestinal system
Short-term disruptions to your circadian rhythm may result in problems with memory or lack of energy. It may also take longer to heal an injury if you don’t get enough sleep.
There are several reasons you may want to talk to a doctor about an issue with your circadian rhythm. If you experience one of these issues for a prolonged period, consider making a doctor’s appointment:
- Have trouble achieving adequate 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. Living a healthy, active lifestyle that promotes proper rest will help you maintain this important component of your body.
Reach out to your 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.