The types of circadian rhythm disorders are advanced or delayed sleep-wake phase disorder, irregular or non–24-hour sleep-wake rhythm disorder, and shift work or jet lag disorder. The type you may have is based on your pattern of sleep and wakefulness.
To better understand circadian disorders, read our How Sleep Works Health Topic.
If you have advanced sleep-wake phase disorder (ASWPD), you may find it very difficult to stay awake in the early evening and wake up too early in the morning. This can interfere with work, school, or social responsibilities.
This is one of the most common circadian rhythm disorders. If you have delayed sleep-wake phase disorder (DSWPD), you may fall asleep later than you would like and find it difficult to wake up on time in the morning. Delayed sleep-wake phase disorder often interferes with work, school, or social responsibilities. You may get too little sleep, which can lead to daytime tiredness or anxiety.
If you have irregular sleep-wake rhythm disorder (ISWRD), you may have several short periods of sleep and wakefulness. You may be unable to sleep during the night and take multiple naps during the day due to excessive sleepiness. You may not feel rested after sleep.
This is often a temporary disorder that may affect you if you travel across at least two time zones in a short period. Your sleep-wake rhythm is out of sync with the local time at your destination, so you may feel sleepy or alert at the wrong time of day or night. Jet lag disorder is often more severe when you travel east, compared with traveling west.
Some people experience social jet lag, in which activities on weekends or days off occur at much later times than on weekdays or workdays. This is not considered a disorder.
This type of circadian rhythm disorder occurs when a person’s sleep-wake rhythm is not in sync with the 24-hour day. When this happens, your sleep times may gradually become more delayed. For example, your sleep time may be delayed to the point that you are going to sleep at noon instead of night. This often happens when light exposure is very limited, and it is common in people who are completely blind. You may have periods of insomnia and daytime sleepiness, followed by periods with no symptoms, when your circadian rhythms happen to align with your environment.
Shift work disorder affects those who work during the night or on a rotating schedule. Because of your work schedule, you may not be able to get uninterrupted quality sleep when your body needs it. Shift work disorder can cause insomnia, fatigue, and sleepiness while working at night.
Circadian rhythm disorders occur when your sleep-wake cycle is out of sync with your environment. Many factors, both internal and external, can cause you to have problems sleeping and raise your risk for a circadian rhythm disorder.
Genetic conditions that affect your brain or hormones can cause circadian rhythm disorders. For example, Smith-Magenis syndrome is a genetic condition that may affect how much or how often your body makes the hormone melatonin, which helps you sleep. Sleep patterns may be completely reversed, causing daytime sleepiness and wakeful nights.
Did you know that your natural circadian rhythm and your risk for disorders may be different from someone else’s?
The sleep-wake cycle can be different for different people. Some people naturally wake early, while others naturally stay up late. These patterns are controlled by your genes, among other factors. You may develop circadian rhythm disorders if your patterns do not align with your work, school, or social responsibilities. Some people can more easily adjust their circadian rhythm to match their environment. This adaptable nature makes you less likely to develop jet lag disorder and shift work disorder.
You may have a higher risk for circadian rhythm disorders because of internal factors such as your age, your sex, family history and genetics, and certain medical conditions that affect your brain or vision. External factors such as your lifestyle habits, environment, and occupation can also increase your risk.
The rhythm and timing of your sleep-wake cycle can change with age because of changes in your brain. Teens may naturally have a later bedtime than adults, which raises their risk for delayed sleep-wake phase disorder. Older adults, on the other hand, usually sleep and wake up early. This raises their risk for advanced sleep-wake phase disorder. Older adults are also at higher risk for shift work disorder and jet lag disorder.
People who work during the night have a higher risk for shift work disorder. Jet lag disorder is more common in pilots, flight attendants, athletes, and people who travel often for business.
Your genes may play a role in whether you naturally wake up early in the morning or go to sleep later at night. This genetic preference of an early or late bedtime can raise your risk for advanced or delayed sleep-wake phase disorder if your rhythm is out of sync with your environment or social responsibilities.
Mutations in certain genes can also raise your risk for circadian rhythm disorders. These include the genes that control your body’s circadian clocks and certain genes that affect brain development or health.
Lifestyle habits can raise your risk for circadian rhythm disorders. These include:
Several medical conditions can increase your risk for circadian rhythm disorders, including:
How do neurodegenerative conditions lead to circadian rhythm disorders?
Neurodegenerative diseases such as Alzheimer’s disease and dementia can damage brain cells that process light and other signals from the environment. Without correct information, your body makes less melatonin and at different times of the day than expected. This can lead to irregular sleep-wake rhythm disorder or a complete reversal of the normal sleep-wake cycle.
People who have neurodegenerative conditions and are living in nursing homes may not have a clear pattern of day and night. They may have few social interactions during the day and be awakened for medicine and care throughout the day and night. This can lead to a disrupted sleep-wake cycle, which may cause circadian rhythm disorders.
Men are more likely to have advanced sleep-wake phase disorder than women.
Women may be more likely to experience circadian rhythm disorders at certain stages of life.
Currently, there are no screening methods to determine who will develop circadian rhythm disorders. Your doctor may ask you about your sleep habits in childhood and the last several years, and if you have performed shift-work. If you are at risk for circadian rhythm disorders, your doctor may recommend certain lifestyle changes to help prevent a circadian rhythm disorder.
To help lower your risk of circadian rhythm disorders, your doctor may recommend that you make healthy lifestyle changes and avoid bright light and caffeine close to your bedtime. While caring for a newborn at night, keep the lights as dim as possible.
You may be able to prevent a circadian rhythm disorder caused by external factors such as your environment.
The following steps may help prevent shift work disorder:
The following steps may help prevent jet lag disorder:
Signs and symptoms of circadian rhythm disorders can vary depending on the type of circadian rhythm disorder you have and how severe your condition is. Many of the symptoms of circadian rhythm disorders occur because you are not getting enough good-quality sleep when your body needs it. Undiagnosed and untreated circadian rhythm disorders may increase your risk of certain health conditions or cause workplace or road accidents.
Common symptoms of circadian rhythm disorders include:
How do circadian rhythm disorders affect judgment?
Circadian rhythm disorders often cause sleep deficiency, a condition in which you do not get the recommended amount of uninterrupted quality sleep. Sleep deprivation can change how well your brain judges risky situations and behaviors. When you do not get enough sleep, you may underestimate the risks and overestimate the rewards of certain situations. This may lead you to make riskier choices than you would have made if you were well rested. Not getting enough sleep when you need it can also increase your risk for accidents, such as those caused by drowsy driving after working a night shift, for example.
Circadian rhythm disorders may increase your risk for the following health conditions:
Do you want to learn more about how circadian rhythm disorders cause problems with metabolism in shift workers?
When shift work triggers a circadian rhythm disorder, it can disrupt your metabolism in a few ways. Normally, your biological clock helps control your hunger hormones. However, when you do not get enough good-quality sleep, your body makes less leptin, the hormone that tells your body when you are full, and more ghrelin, the hormone that tells your body you are hungry. You may respond by eating larger amounts of food than normal, as well as more fatty, sweet, and salty foods.
To diagnose a circadian rhythm disorder, your doctor may review your medical history; ask about your symptoms, sleep patterns, and environment; do a physical exam; and order diagnostic tests.
Your doctor will want to learn about your signs and symptoms, risk factors, your personal health history, and your family health history to help diagnose a circadian rhythm disorder. To do this, your doctor may do the following:
Your doctor may have you undergo or use some of the following tests and measurements:
Do you want to learn more about how melatonin, cortisol, and body temperature work in someone with a healthy sleep cycle?
When you have a healthy sleep pattern, melatonin levels usually start to rise about two hours before your normal bedtime. Melatonin reaches its highest level while you sleep and goes down as you wake up. Your cortisol levels are usually highest early in the morning and fall throughout the day. Cortisol helps prepare your body to wake up. Body temperature typically falls during the night and rises in the early hours of the morning. All these changes are controlled by your circadian clocks.
To rule out other causes of your symptoms, your doctor may do the following:
Treatments for circadian rhythm disorders aim to reset your sleep-wake rhythm to align with your environment. Your treatment plan will depend on the type and severity of your circadian rhythm disorder. The most common treatments are healthy lifestyle changes, bright light therapy, and melatonin. Often, your doctor will recommend a combination of these treatments.
To help reset your sleep-wake cycle, your doctor may recommend that you establish a daily routine with set activities that happen during the day and another set of activities that happen at night. This may help manage the symptoms of circadian rhythm disorders caused by internal or external factors. A daily routine is especially important if you have complete blindness or cannot tolerate changes to your light exposure. Your daily routine may include:
Your doctor may suggest that you try light therapy to treat some types of circadian rhythm disorders. With this approach, you plan time each day to sit in front of a light box, which produces bright light similar to sunlight. Light visors and light glasses may also be effective. Light therapy may help adjust how much melatonin your body makes to reset your sleep-wake cycle.
Side effects of light therapy may include agitation, eye strain, headaches, migraines, and nausea. Ask your doctor before using light therapy if you have an eye condition or use medicines that make you sensitive to light.
Your doctor may recommend melatonin medicines or supplements to help align your sleep-wake cycle with your environment. The choice depends on the type and severity of your circadian rhythm disorder. Options may include the following:
These medicines may not be recommended for people who have dementia or epilepsy, or who take the blood thinning medicine warfarin. Other people who need to consult a doctor before taking these medicines include women who are pregnant, trying to become pregnant, or breastfeeding.
Other medicines which may be used to treat the symptoms of circadian rhythm disorders include:
If you have been diagnosed with a circadian rhythm disorder, it is important that you continue your treatment. Follow-up care can vary depending on your response to treatment and whether your condition is caused by internal factors, such as a medical condition, or external factors, such as your environment.
It is important that you follow your doctor’s instructions to help avoid the symptoms and complications of circadian rhythm disorders. You may need to maintain a regular daily schedule, take your medicines as prescribed, and follow your doctor’s instructions for light therapy even when your condition improves. If your circadian rhythm disorder continues after appropriate lifestyle changes and treatments, you may need to adapt your daily routine to an early or late sleep phase.
Talk with your doctor about how often to schedule office visits and medical tests. Between visits, tell your doctor if you have any new symptoms, if your symptoms worsen, or if you have any complications because of your medicines.
Return to Treatment to review possible treatment options for your circadian rhythm disorder.
To monitor your condition and to help prevent complications, your doctor may recommend regular testing. These tests and measurements may include:
Your doctor may also recommend that you keep a sleep diary to monitor improvements in your pattern of sleep and wakefulness and in your quality of sleep.
To avoid accidents caused by fatigue and daytime sleepiness, it is important to identify when you are too tired to drive, operate heavy machinery, or work. Consider using public transportation if you are too tired to drive.
Learn about the following ways the NHLBI continues to translate current research into improved health for people who have circadian rhythm disorders. Research on this topic is part of the NHLBI’s broader commitment to advancing sleep science and sleep disorders scientific discovery.
Learn more about how the NHLBI is contributing to knowledge about circadian rhythm disorders.
In support of our mission, we are committed to advancing circadian rhythms disorders research in part through the following ways:
Learn about exciting research areas the NHLBI is exploring about circadian rhythm disorders.
We lead or sponsor many studies relevant to circadian rhythm disorders. See if you or someone you know is eligible to participate in our clinical trials.
After reading our Circadian Rhythm Disorders Health Topic, you may be interested in additional information found in the following resources.