Circadian Rhythm Disorders

Also known as Sleep-Wake Cycle Disorders
Circadian rhythm disorders are problems that occur when your sleep-wake cycle is not properly aligned with your environment and interferes with your daily activities.

You have a biological clock that controls the timing of several activities and functions of your body, including when you go to sleep and wake up. This internal mechanism is called the circadian clock. The circadian clock cycles about every 24 hours. These repeating 24-hour cycles are called the circadian rhythm. The control of your circadian rhythm is a function of certain genes in the DNA called circadian clock genes.

Your body tries to align your sleep-wake cycle to cues from the environment, for example, when it gets light or dark outside, when you eat, and when you are physically active. When your sleep-wake cycle is out of sync with your environment, you may have difficulty sleeping, and the quality of your sleep may be poor. Disruptions of your sleep-wake cycle that interfere with daily activities may mean that you have a circadian rhythm disorder.

Disruptions in your sleep patterns can be temporary and caused by external factors such as your sleep habits, job, or travel. Or a circadian rhythm disorder can be long-term and caused by internal factors such as your age, your genes, or a medical condition. Symptoms may include extreme daytime sleepiness, insomnia, tiredness, decreased alertness, and problems with memory and decision-making.

To diagnose a circadian rhythm disorder, your doctor may ask about your sleep habits, suggest sleep tests, a diary to track when and how long you sleep, and test the levels of certain hormones in your blood or saliva. Your treatment plan will depend on the type and cause of your circadian rhythm disorder. Treatment may include light therapy, medicines to help you fall asleep or stay awake, or healthy lifestyle changes including steps to improve your sleep habits. If left untreated, circadian rhythm disorders may increase the risk of certain health problems or lead to workplace and road accidents.

Explore this Health Topic to learn more about circadian rhythm disorders, our role in research and clinical trials to improve health, and where to find more information.

Types - Circadian Rhythm Disorders

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.

Advanced sleep-wake phase disorder
- Circadian Rhythm Disorders

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.

Delayed sleep-wake phase disorder
- Circadian Rhythm Disorders

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.

Irregular sleep-wake rhythm disorder
- Circadian Rhythm Disorders

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.

Jet lag disorder
- Circadian Rhythm Disorders

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.

Non–24-hour sleep-wake rhythm disorder
- Circadian Rhythm Disorders

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
- Circadian Rhythm Disorders

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.

Causes - Circadian Rhythm Disorders

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?

Look for
- Circadian Rhythm Disorders

  • Risk Factors will discuss medical conditions, lifestyle habits, and other factors that can increase your chance of developing a circadian rhythm disorder.
  • Treatment will discuss healthy lifestyle changes and medicines that your doctor may recommend if you are diagnosed with a circadian rhythm disorder.

Risk Factors - Circadian Rhythm Disorders

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.

Age
- Circadian Rhythm Disorders

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.

Environment or occupation
- Circadian Rhythm Disorders

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.

Family history and genetics
- Circadian Rhythm Disorders

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
- Circadian Rhythm Disorders

Lifestyle habits can raise your risk for circadian rhythm disorders. These include:

  • Alcohol use
  • Chronic caffeine use
  • Frequent air travel
  • Illegal drug use
  • Lack of exposure to natural light during the day
  • Unhealthy sleep habits such as regularly staying up late and nighttime exposure to artificial light, including light from a TV screen, a smartphone, or a very bright alarm clock

Other medical conditions
- Circadian Rhythm Disorders

Several medical conditions can increase your risk for circadian rhythm disorders, including:

  • Autism spectrum disorders
  • Certain genetic conditions, such as Smith-Magenis syndrome, Angelman syndrome, and Huntington’s disease
  • Conditions that affect eyesight, such as blindness and macular degeneration. This raises the risk for non-24-hour sleep-wake rhythm disorder.
  • Conditions that cause damage to the brain, such as traumatic brain injuries, strokes, and brain tumors
  • Mental health conditions, such as bipolar disorder, major depression, obsessive-compulsive disorder, and schizophrenia. This raises the risk of delayed sleep-wake phase disorder.
  • Neurodegenerative diseases, such as Alzheimer’s disease, dementia, and Parkinson’s disease. These conditions are more common in older adults and can increase your risk for irregular sleep-wake phase disorder.

How do neurodegenerative conditions lead to circadian rhythm disorders?

Sex
- 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.

  • Hormonal changes that happen during pregnancy, after childbirth, and at menopause can cause problems with sleep.
  • Discomfort during pregnancy may also prevent good-quality sleep.
  • After childbirth, sleep interruptions and nighttime exposure to light while caring for a newborn can increase your risk for circadian rhythm disorders.

Screening and Prevention - Circadian Rhythm Disorders

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.

Preventive strategies
- Circadian Rhythm Disorders

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:

  • Take a short nap before your night shift to help prevent sleepiness at work.
  • Adopt a sleep schedule on your days off that overlaps with your sleep time on work days.
  • Avoid multiple schedule switches between day and night shifts, if possible.

The following steps may help prevent jet lag disorder:

  • A few days before traveling across several time zones, begin adjusting your sleep-wake cycle to match the time at your destination. You may gradually change your sleep schedule and use bright light to help advance or delay your waking time.
  • If you can, arrive at your destination a few days before an important event, to help you gradually adjust to the local time. Your body adjusts to the time at your destination at a rate of 1 to 1.5 time zones per day.
  • Spend plenty of time outside at your destination. Outdoor light may shorten symptoms of jet lag.

Look for
- Circadian Rhythm Disorders

  • Diagnosis will discuss tests and procedures that your doctor may use to diagnose types of circadian rhythm disorders.
  • Living With will discuss what your doctor may recommend to prevent your circadian rhythm disorders from recurring, getting worse, or causing complications.
  • Research for Your Health will discuss how we are using current research and advancing research to prevent circadian rhythm disorders.
  • Participate in NHLBI Clinical Trials will discuss our open and enrolling clinical studies that are investigating prevention strategies for circadian rhythm disorders.

Signs, Symptoms, and Complications - Circadian Rhythm Disorders

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.

Signs and symptoms
- Circadian Rhythm Disorders

Common symptoms of circadian rhythm disorders include:

  • Consistent difficulty falling asleep, staying asleep, or both
  • Excessive daytime sleepiness or sleepiness during shift work
  • Fatigue and exhaustion
  • Lethargy
  • Decreased alertness and difficulty concentrating
  • Impaired judgment and trouble controlling mood and emotions
  • Aches and pains, including headaches
  • Stomach problems, in people who have jet lag disorder

How do circadian rhythm disorders affect judgment?

Complications
- Circadian Rhythm Disorders

Circadian rhythm disorders may increase your risk for the following health conditions:

  • A weakened immune system, which can lead to infections and poor recovery from illnesses
  • Cardiovascular diseases, such as atherosclerosis or stroke
  • Cognitive and behavioral disorders, such as decreases in attention, vigilance, concentration, motor skills, and memory. These can lead to reduced productivity, workplace mistakes, or road accidents. In teens and young adults, circadian rhythm disorders can cause risky behavior and problems with concentrating at school, controlling emotions, and coping with stress.
  • Digestive disorders, such as stomach ulcers, gastroesophageal reflux disease (GERD), and irritable bowel syndrome. Circadian rhythm disorders may influence the signaling from the brain to the gastrointestinal tract. They may also increase inflammation in the bowel, which can lead to digestive symptoms.
  • Fertility problems. Circadian rhythm disorders may disrupt the hormone cycle that controls fertility and reproduction.
  • Metabolism disorders, which can lead to diabetes, metabolic syndrome, and overweight and obesity
  • Mood disorders, including irritability, anxiety, and depression
  • Worsening of other sleep disorders, such as sleep apnea

Do you want to learn more about how circadian rhythm disorders cause problems with metabolism in shift workers?

Look for
- Circadian Rhythm Disorders

  • Diagnosis will discuss tests and procedures used to detect signs of circadian rhythm disorders and help rule out other conditions that may mimic circadian rhythm disorders.
  • Treatment will discuss treatment-related complications or side effects.

Diagnosis - Circadian Rhythm Disorders

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.

Medical history and physical exam
- Circadian Rhythm Disorders

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:

  • Ask when, how long, and how well you sleep.
  • Ask when your symptoms began. Symptoms that have lasted for three months or more may indicate a circadian rhythm disorder.
  • Ask about your personal and family history of health conditions.
  • Perform a physical examination.

Diagnostic tests
- Circadian Rhythm Disorders

Your doctor may have you undergo or use some of the following tests and measurements:

  • A sleep diary to help you keep track of when and how long you sleep
  • Actigraphy, in which you wear a small motion sensor for three to 14 days to measure your sleep-wake cycles
  • Sleep studies to measure how well you sleep and how your body responds to sleep problems.
  • Other studies to look at your natural patterns of sleep and wakefulness. Your doctor may repeatedly measure your body temperature and the levels of melatonin and cortisol in your blood or saliva. The way these factors rise and fall over time can help determine the type of circadian rhythm disorder you may have.

Do you want to learn more about how melatonin, cortisol, and body temperature work in someone with a healthy sleep cycle?

Ruling out other medical conditions
- Circadian Rhythm Disorders

To rule out other causes of your symptoms, your doctor may do the following:

  • Ask about your use of caffeine, nicotine, alcohol, or illegal drugs, as well as your exposure to artificial light at night. These lifestyle habits may cause insomnia or tiredness.
  • Ask you to keep a sleep diary or have a specific type of sleep study to rule out other problems with sleep, such as insomnia, sleep apnea, and narcolepsy
  • Ask you whether you have chronic pain that may be preventing good-quality sleep
  • Examine you for heart or lung conditions that may prevent good-quality sleep
  • Examine you for large tonsils or small airways to help rule out sleep apnea
  • For women, ask whether you are pregnant or undergoing menopause

Reminders
- Circadian Rhythm Disorders

  • Return to Risk Factors to review family history, lifestyle, or other environmental factors that increase your risk of developing circadian rhythm disorders.
  • Return to Signs, Symptoms, and Complications to review common signs and symptoms of circadian rhythm disorders.

Treatment - Circadian Rhythm Disorders

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.

Healthy lifestyle changes
- Circadian Rhythm Disorders

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:

  • Adopting a regular meal schedule, especially if you are a shift worker or sleep at irregular times of the day or night.
  • Adopting a regular bedtime routine. Sleep in a cool, quiet place and follow a relaxing bedtime routine that limits stress. These practices, along with regular sleep and waking times, can help you fall asleep faster and stay asleep longer.
  • Avoiding daytime naps, especially in the afternoon. However, shift workers may benefit from a short nap before the start of their shift.
  • Exercising regularly. Your doctor may recommend getting regular physical activity during the daytime and avoiding exercising close to bedtime, which may make it hard to fall asleep.
  • Limiting your intake of caffeine, alcohol, nicotine, and some medicines, especially close to bed time
  • Managing your exposure to light. Light is the strongest signal in the environment to help reset your sleep-wake cycle. You may need more sunlight during the day and less artificial light at night from TV screens and electronic devices. Artificial light can lower your melatonin levels, making it harder to fall asleep. Light-blocking glasses, screen filters, or smartphone apps can help dim the light from your electronic devices. Dim lighting for a period before bed may also help reduce the symptoms of a circadian rhythm disorder. For shift workers, wearing light-blocking glasses when you are outside during the day may help.

Light therapy
- Circadian Rhythm Disorders

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.

  • To move your sleep and wake times earlier, use the light box when you wake up in the morning. This may also help reduce daytime sleepiness. This method may be used to help treat delayed sleep-wake phase disorder, irregular sleep-wake rhythm disorder, and jet lag disorder when you travel east.
  • To move your sleep and wake times later, use the light box late in the afternoon or early in the evening. This method may be used to help treat advanced sleep-wake phase disorder, shift work disorder, and jet lag disorder when you travel west.

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.

Melatonin medicines or supplements
- Circadian Rhythm Disorders

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:

  • Melatonin receptor agonists are medicines to treat non–24-hour sleep-wake rhythm disorder. Side effects can include dizziness and fatigue.
  • Melatonin supplements are lab-made versions of the sleep hormone that your doctor may recommend to treat delayed sleep-wake phase disorder, irregular sleep-wake rhythm disorder, and non–24-hour sleep-wake rhythm disorder. These supplements are not regulated by the U.S. Food and Drug Administration. Thus, the dose and purity of these supplements can vary. Talk with your doctor about how to find safe, effective melatonin supplements, as well as any possible side effects or medicine interactions. Side effects of melatonin may include excess sleepiness, headaches, high blood pressure, low blood pressure, stomach upsets, and worsening symptoms of depression.

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:

  • Beta blockers to reduce the levels of melatonin in your body during the day
  • Caffeine to help prevent daytime sleepiness. Your doctor may recommend that you avoid caffeine within eight hours of your desired bedtime.
  • Sleep-promoting medicines, such as benzodiazepines and zolpidem, to help you fall asleep faster and stay asleep longer. These medicines may cause side effects and complications that may be more severe in older adults and people who have dementia. These complications can include confusion, headaches, poor medicine interactions, long-term dependence, muscle weakness, falls, and nausea.
  • Wake-promoting medicines, such as modafinil and armodafinil, to help you stay alert and improve performance during shift work. The effects of these medicines may last only for a short time, and you may still experience some sleepiness.

Look for
- Circadian Rhythm Disorders

  • Research for Your Health will discuss how we are using current research and advancing research to treat people who have circadian rhythm disorders.
  • Participate in NHLBI Clinical Trials will discuss our open and enrolling clinical studies that are investigating treatments for circadian rhythm disorders.
  • Living With will discuss what your doctor may recommend including lifelong lifestyle changes and medical care to prevent your condition from recurring, getting worse, or causing complications.

Living With - Circadian Rhythm Disorders

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.

Follow your treatment plan
- Circadian Rhythm Disorders

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.

Receive routine follow-up care
- Circadian Rhythm Disorders

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.

Monitor your condition
- Circadian Rhythm Disorders

To monitor your condition and to help prevent complications, your doctor may recommend regular testing. These tests and measurements may include:

  • Actigraphy testing to check periods of sleep and activity
  • Body weight
  • Melatonin levels
  • Metabolism

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.

Learn precautions to help you stay safe
- Circadian Rhythm Disorders

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.

Research for Your Health

The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discoveries to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including circadian rhythm disorders. Learn about current and future NHLBI efforts to improve health through research and scientific discovery.

Improving health with current research
- Circadian Rhythm Disorders

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.

  • NHLBI’s National Center on Sleep Disorders Research (NCSDR). For 25 years, the NCSDR has led foundational research on sleep and circadian biology across the NIH and has worked with federal and private organizations to disseminate sleep health information. The NCSDR administers sleep and circadian research projects, training, and educational awareness programs, and serves as an NIH point of contact for federal agencies and public interest organizations. The Center also participates in research translation and dissemination of scientific sleep and circadian advances to healthcare professionals, public health officials, and the public.
  • Advancing Circadian Rhythm Research. We have organized workshops to help direct future research into circadian rhythms and circadian rhythm disorders. These workshops have brought together experts in the fields of sleep and circadian rhythm research to identify pertinent areas of research into the role of circadian rhythms in the development and progression of several health conditions. Learn more about Developing Biomarker Arrays Predicting Sleep and Circadian-Coupled Risks to Health and Circadian-Coupled Cellular Function and Disease in Heart, Lung, and Blood.
  • Investigating the Link between Circadian Rhythms and Lung Diseases. We have hosted workshops to address current gaps in our understanding of acute and chronic lung diseases. Our workshops have helped direct research to build upon preliminary discoveries showing that lung diseases such as asthma may be influenced by circadian rhythms. Learn more about The Circadian Clock’s Influence on Lung Health.
  • Research Conference on Sleep and the Health of Women. This 2018 conference focused on the importance of sleep for women’s health. It showcased a decade of federally funded research advances in understanding the health risks, societal burden, and treatment options associated with sleep deficiency and sleep disorders in women. Topics discussed at this conference included the influence of sleep and circadian rhythms on alcohol consumption and cancer in women, and the social, environmental, and biological factors that affect sleep in women, including during pregnancy, postpartum, and menopause. Learn more from the Research Conference on Sleep and the Health of Women.
  • Improving the Quality of Medical School Education on Sleep Disorders. As part of its efforts to ensure that research advances are utilized by healthcare providers, the NCSDR has supported the development of medical school curricula and durable educational materials on sleep disorders, including circadian rhythm disorders.
  • Sleep Disorders Research Advisory Board (SDRAB). The NHLBI has administered this specialty program advisory panel since 1993. Board members, including medical professionals, federal partners, and members of the public, meet regularly to provide feedback to the NIH on sleep-related research needs and to discuss how to move sleep research forward. The SDRAB has supported advances to improve our understanding of circadian rhythms and circadian rhythm disorders. Visit the Sleep Disorders Research Advisory Board for more information.
  • National Sleep Research Resource (NSRR). This resource was established by the NHLBI to provide biomedical researchers a large, well-characterized data collection from NIH-funded sleep research studies. These data can be used in new research studies to advance sleep research, including research into circadian rhythm disorders. Visit the National Sleep Research Resource for more information.

Learn more about how the NHLBI is contributing to knowledge about circadian rhythm disorders.

Advancing research for improved health
- Circadian Rhythm Disorders

In support of our mission, we are committed to advancing circadian rhythms disorders research in part through the following ways:

  • We perform research. Our Division of Intramural Research, which includes investigators from the Systems Biology Center, and its Systems Genetics Laboratory, performs research on circadian rhythm disorders.
  • We fund research. The research we fund today will help improve our future health. Our Division of Lung Diseases and its National Center on Sleep Disorders Research oversee much of the research on circadian rhythm disorders we fund, helping us to understand the importance of circadian rhythms and their influence on our health and well-being. Search the NIH RePORTer to learn about research the NHLBI is funding on circadian rhythm disorders.
  • We stimulate high-impact research. The NHLBI Strategic Vision highlights ways we may support research over the next decade. We are funding new efforts to understand the role of circadian rhythms in controlling normal functions of the body. This research will help improve our understanding of how sleep disorders such as circadian rhythm disorders can cause various health conditions.

Learn about exciting research areas the NHLBI is exploring about circadian rhythm disorders.

Participate in NHLBI Clinical Trials

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.

Are you an adult with a diagnosed sleep phase disorder?

This study aims to assess the sleep patterns and quality of sleep in people who have sleep phase disorders to determine how the disorders affect their circadian rhythms. To participate in this study, you must be at least 18 years old and have a sleep phase disorder, such as advanced sleep-wake phase syndrome or delayed sleep-wake phase syndrome. This study is located in Chicago, Illinois.

Are you a healthy adult who regularly sleeps for 6.5 or fewer hours?

This study is examining whether getting enough sleep can lower your risk of high blood pressure. To participate in this study, you must be between 18 and 65 years old, regularly sleep for 6.5 or fewer hours, and be able to adjust your sleep schedule for the study. This study is located in Rochester, Minnesota.

Do you have overweight?

Circadian rhythm disorders can cause overweight and obesity. This study is examining how not getting enough sleep causes these complications. To participate in this study, you must be between the ages of 20 and 40 and have overweight but not obesity. This study is located in New York, New York.

Are you an adult who does not work nights?

This study is examining how a person’s sleep schedule affects circadian rhythms, learning skills, physical ability, and mood. To participate in this study, you must be between 18 and 35 years old and not have underweight or obesity. This study is located in Boston, Massachusetts.

Are you an adult who does not have high blood pressure?

Circadian rhythms control daytime and nighttime changes in blood pressure. This study is examining the links between stress, loss of sodium through urine, and circadian rhythms in controlling blood pressure. To participate in this study, you must be at least 21 years old and not have high blood pressure. This study is located in New York, New York.

More Information

After reading our Circadian Rhythm Disorders Health Topic, you may be interested in additional information found in the following resources.

Non-NHLBI resources
- Circadian Rhythm Disorders

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