Circadian rhythm disorder (exams and assessments)

What are circadian rhythm disorders?

Circadian rhythm disorders are problems with your circadian rhythm, the “internal clock” that keeps your biological processes going. Your normal circadian rhythm is determined by the light-dark cycle over 24 hours. It plays a key role in sleeping and waking up. Patterns of brain waves, hormone production, cell re-generation, and other activities are associated with this cycle.

People with circadian rhythm disturbances can have problems:

  • Fall asleep
  • Sleep through
  • Waking up too early and being unable to fall asleep
  • Fall asleep but not feel refreshed
  • Feeling awake during the day

Other symptoms can include:

Causes of the circadian rhythm disorder

Things that can cause circadian rhythm disturbances are:

Common circadian rhythm disturbances

  • Jet lag, or syndrome of rapid time zone change. This includes symptoms such as excessive sleepiness and lack of vigilance during the day in people traveling across time zones. It gets worse with each time zone you traverse, especially as you travel east.

  • Sleep disorder when working shifts. This sleep disorder affects people who often work alternating shifts or work at night. A conflict between a person’s circadian rhythm and the time of their shift can result in up to 4 hours less sleep than the average person.
  • Delayed Sleep Phase Syndrome (DSPS). This is a sleep timing disorder. People with DSPS tend to fall asleep very late at night and find it difficult to wake up in time for work, school, or social events. It is especially common in teenagers and young adults.
  • Advanced Sleep Phase Syndrome (ASPS). This is a disorder where a person falls asleep earlier and wakes up earlier than they wanted. For example, they might fall asleep between 6 p.m. and 9 p.m. and wake up between 1 a.m. and 5 a.m.
  • Non-24-hour sleep-wake disorder. This disorder often affects the blind, as the circadian clock is set by the light-dark cycle. With this condition, this cycle is disturbed. It can lead to a serious lack of sleep time and quality at night and drowsiness during the daytime hours.
  • Irregular sleep-wake rhythm disorder. With this disorder, people’s circadian rhythms are jumbled. You can sleep in a series of naps over 24 hours.


Diagnosing a circadian rhythm disorder

Talk to your doctor if:

  • You sleep poorly for more than 1 month and notice difficulty concentrating, forgetfulness, reduced motivation or severe daytime sleepiness
  • You have difficulty falling asleep
  • You wake up tired and sleepless in the morning

Your doctor will first ask about your symptoms, take a medical history, and do a physical exam.

You can also use:

  • Sleep logs. A sleep log identifies the sleep-wake cycles in your normal environment (when you are at home and not traveling or working odd hours). You will be asked to write down when and how well you sleep over a period of time.
  • Sleep studies. Usually done in a sleep laboratory, sleep studies monitor you while you sleep, measure oxygen levels, the frequency with which you stop breathing, and how much you snore.
  • Imaging studies, such as CT scans and MRIs, can be used to check for neurological disorders, sinus infections, or blocked airways.
  • Epworth Sleepiness Scale. This questionnaire rates responses to eight situations on a scale of 0-3 for their associations with sleepiness.
  • Actigraphy. You will wear a motion sensor on your non-dominant wrist for a week to measure your sleep-wake cycle.

Treatments for circadian arrhythmias

Your treatment will depend on your condition. The goal is to fit your sleep pattern into a schedule that fits your lifestyle. Treatments can be:

  • light therapy. You reset your rhythm by being around a light for a specific amount of time each day.
  • Sleep hygiene. You will learn how to improve your circadian rhythm by changing your bedtime or sleeping environment.
  • Chronotherapy. You will slowly adjust your bedtime until it reaches the time you want.
  • Lifestyle changes. Things like planning naps, being careful with light, and avoiding caffeine or nicotine for some time before bed can help.

Medications used to treat circadian rhythm disorders include:

This natural hormone is made by a gland in the brain at night (when it’s dark). The level of in the body is low during the day and high at night.

supplements, available over the counter, may be helpful in treating jet lag and insomnia in the elderly with melatonin deficiency. But they haven’t been approved by the FDA, so it’s not clear how much melatonin is safe and effective.


Melatonin receptor stimulant

Rozerem, a melatonin receptor stimulant, requires a doctor’s prescription. It is FDA approved for the treatment of insomnia, which is characterized by difficulty falling asleep.


Short-acting benzodiazepines such as Xanax are often prescribed for the early treatment of a circadian rhythm disorder and are used in conjunction with behavioral therapy. Long-term use is not recommended due to possible side effects such as the rebound phenomenon (the original problem returns at a higher level) and the risk of addiction.

Non-benzodiazepine hypnotics

These prescription sleep aids like Ambien, Sonata, and Lunesta are not associated with the rebound phenomenon seen with benzodiazepines. However, the FDA has warned that people who take them have experienced “rare but serious injuries” resulting from “complex sleep behaviors” such as sleepwalking and sleep driving.

Orexin receptor antagonists

Orexins are chemicals that help regulate your sleep-wake cycle and help you stay awake. This type of medicine changes the way orexin works in the brain. The only approved drug in this class is Belsomra.


If you suffer from a circadian rhythm disorder due to shift work, your doctor may prescribe this stimulant. You take it an hour before your shift starts to feel more awake.



eMedicine health.

National Foundation for Sleep.

American sleep bandage.

American Academy of Sleep Medicine: “Circadian Rhythm Sleep Disorders Fact Sheet”.

Continuum: “Circadian rhythm anomalies.”

Cleveland Clinic: “Circadian Rhythm Disorders”.

Chest: “wrist actigraphy”.

Journal of Clinical Outcomes Management: “Circadian Rhythm Sleep Disorders”.

Press release, FDA.

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