Circadian rhythm sleep disorders | You and Your Hormones from the Society for Endocrinology (2023)

Alternative names for circadian rhythm sleep disorders

Advanced sleep phase disorder; delayed sleep phase disorder; non-24-hour sleep/wake syndrome; free-running sleep/wake patterns

What are circadian rhythm sleep disorders?

Circadian rhythm sleep disorders | You and Your Hormones from the Society for Endocrinology (1)

Melatonin pills can be taken to treat sleep disorders.

The timing, duration and quality of sleep are determined by two physiological processes:

  1. The sleep homeostat, which measures the need to sleep. This builds up during waking time and then disappears during sleep.
  2. The circadian clock, which drives the daily, 24-hour body rhythms in all aspects of physiology and behaviour, including sleep/wake pattern. To be able to get good quality sleep at night requires that our circadian clock is appropriately synchronised with local time.

The time that we go to bed and wake up is generally determined by our work, study and social commitments. So, for the majority of people who work or study on a 9 a.m. to 5 p.m. pattern, a ‘normal’ sleep schedule would probably involve going to bed between 10 p.m. and midnight, and getting up between 6 a.m. and 8 a.m. in the morning. However, sufferers of circadian rhythm sleep disorders have circadian clocks that are not synchronised with such a ‘normal’ sleep schedule; instead their body clock is telling them to go to sleep and wake up at very different times. The relationship between their circadian clock and local time (local light/dark cycles) is abnormal.

Having a circadian rhythm sleep disorder is similar to having permanent jet lag – a misalignment between the body clock, the local clock time and the light/dark cycle. This leads to problems in falling asleep when we want to, staying asleep and feeling fully rested, and also feeling sleepy during waking hours.

What are the signs and symptoms of circadian rhythm sleep disorders?

Sufferers of advanced sleep phase disorder have an ‘early’ circadian clock; they feel sleepy and want to go bed in the early evening (6 p.m. to 9 p.m.) and wake up in the early hours of the morning (2 a.m. to 5 a.m.). Consequently, they may have been awake several hours before they go to work and may not perform well or be alert. They will also feel sleepy in the late afternoon/early evening, which can affect their social lives.

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In contrast, sufferers of delayed sleep phase disorder have a ‘late’ circadian clock; they are unable to fall asleep until the early hours of the morning (4 a.m. to 6 a.m.) and consequently will not awake until approximately midday. This disorder can make it difficult for the individual to get to work or college on time and if they are able to wake up in time, they will probably not have had enough sleep and so will not be alert or perform well. This can lead to growing fatigue.

Sufferers of non-24-hour sleep/wake syndrome do not have a continuous bout of sleep each night but, instead, have several short naps across the day and night.

Individuals with ‘free-running’ sleep patterns will experience a gradual drift each day in the time that they go to bed and wake up. This happens because our circadian clock does not run at exactly 24 hours. It runs at slightly more or slightly less, and environmental light signals at certain times of day are essential to fix it to running at 24 hours. In certain situations, these light signals may not be received or understood and so the circadian clock runs at its own speed. In individuals with clocks longer than 24 hours, this means that they will go to bed and get up progressively later each day and will become unsynchronised to local time.

What causes circadian rhythm sleep disorders?

There are three main causes of circadian rhythm sleep disorders – genetics, the environment and a medical condition. Advanced sleep phase disorder and delayed sleep phase disorder have been associated with specific forms of certain genes in some individuals.

The environment or situation a person finds themselves in can cause temporary circadian-related sleep disorders, for example, jet lag. Night shift workers can also struggle to properly adapt to their altered schedule of sleeping during the day as they often try to maintain daytime family and social commitments as well as their shift work pattern. This causes their body clock to be permanently misaligned with their desired sleep patterns.

Certain medical conditions are also associated with disrupted sleep patterns. For example, many blind people with no light perception suffer from free-running sleep patterns as the body clock does not perceive any environmental light signals and so the clock drifts at its own speed. As the tendency to sleep drifts across the 24-hour day, this can mean individuals are awake at night and sleepy during the day, which can be problematic for going to work or school. Patients with neurodegenerative disorders (e.g. Alzheimer’s and Parkinson’s disease) also experience disturbed sleep/activity patterns. They have increased agitation and pacing around at night, which is known as sundowning and is thought to be due to disruption to the circadian clock.

How common are circadian rhythm sleep disorders?

The number of people who suffer from circadian rhythm disorders in the general population is currently unknown.

Are circadian rhythm sleep disorders inherited?

Advanced sleep phase disorder and delayed sleep phase disorder can be inherited, although environmental factors and age will also have an influence on the frequency and intensity of the disorders within the population.

How are circadian rhythm sleep disorders diagnosed?

An individual who believes they have ‘abnormal’ sleep patterns can consult a specialist. They will be asked to keep a sleep diary for several weeks and possibly wear a small wrist activity monitor that will identify when they are asleep and when they are awake. From these diaries and activity records, a diagnosis should be possible.

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How are circadian rhythm sleep disorders treated?

Treatment of advanced and delayed sleep phase disorder requires the circadian clock to be shifted so it is correctly aligned with local time and the desired sleep/wake schedule, and then held in this position. This can be achieved with a combination of a gradually shifting sleep schedule and light treatment. Bright light has shown to be the most effective mechanism of shifting the timing of the circadian clock.

A delayed sleep phase disorder patient can gradually shift their timing of sleep later and later each day until they reach the desired point, and then they must maintain this schedule. This can be assisted by using a bright light box in the morning when they wake up as this will stop the circadian clock from drifting later in time.

A patient with an advanced sleep phase disorder can gradually advance their sleep schedule until they reach the desired point and then this can be maintained. Using a bright light box in the early evening before bed will prevent the clock from drifting earlier in time. It may also be possible to use precisely scheduled light treatment for non-24-hour sleep/wake syndrome to try and increase the strength and signals from the circadian clock.

There are other ways of aiding restful sleep, sometimes described as developing good sleep hygiene:

  • developing a set routine before bed can help people get to sleep at their desired time
  • as the chosen sleep time approaches, it is important not to engage in stimulating activities such as strenuous exercise or video games
  • heavy meals should also be avoided right before bed. Instead, it is important to try to do relaxing activities before bed, such as a warm bath. Keeping a set routine with a chosen sequence of events (e.g. light snack, bath, change into night clothes, brush teeth, bed) will also ‘teach’ the body when it is time to sleep
  • room temperature can also be important; aperson should feel warm enough in their bed, but the air temperature should be cool
  • doing work or other daytime activities in the bedroom should be avoided as this lessens the subconscious association between the bedroom and sleep
  • caffeine and nicotine should be avoided for several hours before bed if possible, as these are stimulants; there are decaffeinated alternatives to tea or coffee
  • alcohol should be avoided before bed.

Totally blind individuals who exhibit free-running sleep/wake patterns have been shown to benefit from taking melatonin pills at specific times of day. Although melatonin pills are available over the counter in the USA, they are only available on prescription in the UK. Melatonin is able to shift the timing of the body clock and daily administration at a specific time can be used to keep the clock appropriately synchronised to local time. Melatonin must be taken at the correct time of day to achieve the desired effects and avoid unwanted effects.

Are there any side-effects to the treatment?

Gradually delaying (shifting later) or advancing (shifting earlier) the timing of sleep will take a few days and during this time it is necessary to avoid daytime commitments, which could be inconvenient. Fitting a light treatment into a daily schedule may not always be possible but light boxes can be used in conjunction with, or around, other activities such as reading, eating and watching television, which should help. Some individuals can experience headaches or nausea or find the lights in very bright light boxes too bright to use comfortably. New boxes are being developed to try and use lower light intensities that are still effective.

What are the longer-term implications of circadian rhythm sleep disorders?

Some people may be able to adapt their work and social life around their altered sleep patterns so that they do not need to shift their timing of sleep. However, for most people suffering from a circadian rhythm sleep disorder, trying to maintain a normal working life can result in loss of sleep, fatigue and daytime sleepiness. It is possible to shift the timing of sleep and maintain it at an appropriate time, but this will require some changes to an individual’s routine (e.g. using a light box or not scheduling social activities when they should be sleeping).

Last reviewed: Dec 2016


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How circadian rhythm is related to the hormone and endocrine system? ›

Many endocrine factors oscillate in a time-of-day-dependent manner. Endocrine factor rhythms are driven by in part by circadian clocks. Circadian desynchrony is associated with pathologic states. Re-instatement of circadian rhythms improves metabolic homeostasis.

What hormones are affected by circadian rhythm? ›

The regulation and metabolism of several hormones are influenced by interactions between the effects of sleep and the intrinsic circadian system; growth hormone, melatonin, cortisol, leptin, and ghrelin levels are highly correlated with sleep and circadian rhythmicity.

How do you fix a circadian rhythm sleep disorder? ›

The most common treatments are healthy lifestyle changes, bright light therapy, and melatonin. Often, your doctor will recommend a combination of these treatments. We lead or sponsor many studies on sleep disorders, including circadian rhythm disorders.

What are circadian rhythm sleep disorders? ›

Circadian rhythm disorders, also known as sleep-wake cycle disorders, are problems that occur when your body's internal clock, which tells you when it's time to sleep or wake, is out of sync with your environment. Your internal clock, called a circadian clock, cycles about every 24 hours.

How does the endocrine system affect sleep? ›

Sleep and metabolic hormones

Sleep disturbances also produce a rise in ghrelin and a fall in leptin levels, causing an increase in appetite and increased insulin resistance, probably because of disturbed GH levels. Conversely, ghrelin increases SWS and reduces REM sleep in males but not females at all ages.

Which part of the endocrine system helps regulate circadian rhythms? ›

It's a part of your endocrine system and secretes the hormone melatonin. Your pineal gland's main job is to help control the circadian cycle of sleep and wakefulness by secreting melatonin. The pineal gland is shaped like a tiny pinecone, which is how it got its name (“pine”-al gland).

What is the name of the hormone that controls sleep cycles? ›

But when darkness comes at night, the SCN sends messages to the pineal gland. This gland triggers the release of the chemical melatonin. Melatonin makes you feel sleepy and ready for bed.

Which part of the brain controls circadian rhythm? ›

The suprachiasmatic nucleus (SCN) of the mammalian hypothalamus has been referred to as the master circadian pacemaker that drives daily rhythms in behavior and physiology.

Which gland controls the circadian rhythm? ›

The main function of the pineal gland is to receive information about the state of the light-dark cycle from the environment and convey this information by the production and secretion of the hormone melatonin.

What is the fastest way to reset a circadian rhythm? ›

Wake up every day at the same time: Keeping a regular sleep schedule will help reset your circadian rhythm. By going to sleep and waking up at the same time every day, your body will learn to adjust to the new rhythm.

How long does it take to fix my circadian rhythm? ›

How long it takes to reset your circadian rhythm will all depend on how much you're trying to move it by and how quickly you're doing it. We recommend shifting your sleep-wake times by 15 to 30 minutes each night until you reach your ideal schedule. It may take a few days or weeks for your body to fully adjust.

Can melatonin fix circadian rhythm? ›

If you are having a difficult time getting to sleep at a reasonable hour due to a delay in your circadian clock, melatonin is a researched and compelling solution to getting you back on track. According to Johns Hopkins Medicine, the best time to supplement with melatonin is 2 hours before your expected bedtime.

What are the signs of circadian rhythm disorder? ›

Symptoms include excessive sleepiness and lack of daytime alertness. In the circadian rhythm disorder called delayed sleep phase syndrome, patients tend to fall asleep at very late times and have difficulty waking up in time for school.

What is the most common circadian rhythm disorder? ›

Delayed sleep-wake phase disorder

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 then find it difficult to wake up on time in the morning.

What are the 5 major sleep disorders? ›

Key Sleep Disorders
  • Insomnia. Insomnia is characterized by an inability to initiate or maintain sleep. ...
  • Narcolepsy. Excessive daytime sleepiness (including episodes of irresistible sleepiness) combined with sudden muscle weakness are the hallmark signs of narcolepsy. ...
  • Restless Legs Syndrome (RLS) ...
  • Sleep Apnea.

Is circadian rhythm part of the endocrine system? ›

The circadian system, the function of which is controlled by the suprachiasmatic nucleus in the hypothalamus, is integral to a multitude of endocrine and neuroendocrine processes, including metabolism, energy balance and appetite control.

What is the relationship between hormones and the endocrine system? ›

Endocrine glands release hormones into the bloodstream. This lets the hormones travel to cells in other parts of the body. The endocrine hormones help control mood, growth and development, the way our organs work, metabolism , and reproduction. The endocrine system regulates how much of each hormone is released.


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