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Encyclopedia > Circadian rhythm sleep disorder
Circadian rhythm sleep disorder
Classifications and external resources
ICD-10 G47.2
ICD-9 327.3

Circadian rhythm sleep disorders are a family of sleep disorders affecting the timing of sleep. People with circadian rhythm sleep disorders are unable to sleep and wake at the times required for normal work, school, and social needs. They are generally able to get enough sleep if allowed to sleep and wake at the times dictated by their body clocks. Unless they have another sleep disorder, their sleep is of normal quality. The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ...

Humans have biological rhythms, known as circadian rhythms, which are controlled by a biological clock and work on a daily time scale. Due to the circadian clock, sleepiness does not continuously increase as time passes. Instead, the drive for sleep follows a cycle, and the body is ready for sleep and for wakefulness at different times of the day. A circadian rhythm is a roughly-24-hour cycle in the physiological processes of living beings, including plants, animals, fungi and cyanobacteria. ...


Types of circadian rhythm sleep disorders

The circadian rhythm sleep disorders are:

  • Jet lag, which affects people who travel across several time zones.
  • Shift work: People who work at night often have trouble sleeping during the day.
  • Delayed sleep phase syndrome (DSPS), which causes difficulty falling asleep at night and waking up in the morning.
  • Advanced sleep phase syndrome (ASPS), which causes difficulty staying awake in the evening and staying asleep in the morning.
  • Non-24-hour sleep-wake syndrome, which causes patients to stay up later and later each night, then wake up later each morning.
  • Irregular sleep-wake pattern, which presents as sleeping at very irregular times, and usually more than once per day (waking frequently during the night and taking naps during the day).

Jet lag (or jet-lag) is a physical condition caused by crossing multiple time zones during flight. ... Shift work is an employment practice designed to make use of the 24 hours of the clock, rather than a standard working day. ... Delayed sleep-phase syndrome (DSPS) is a chronic sleep disorder in which the patients internal body clock is not in sync with the morning-rise / evening-sleep pattern of the majority of adults. ... Advanced sleep phase syndrome (ASPS) is a sleep disorder in which patients feel very sleepy early in the evening (e. ... Non 24-hour sleep phase syndrome, also termed non 24-hour circadian rhythm disorder or hypernychthemeral syndrome, is a sleep disorder in which a persons internal clock runs longer than 24 hours. ...

Normal circadian rhythms

Among people with healthy circadian clocks, there are "larks" or "morning people" who prefer to sleep and wake early, and there are "owls" who prefer to sleep and wake at late times. Whether they are larks or owls, people with normal circadian systems:

  • can wake in time for what they need to do in the morning, and fall asleep at night in time to get enough sleep before having to get up.
  • can sleep and wake up at the same time every day, if they want to.
  • will, after starting a new routine which requires they get up earlier than usual, start to fall asleep at night earlier too within a few days. For example, someone who is used to sleeping at 1 am and waking up at 9 am begins a new job on a Monday, and must get up at 6 am to get ready for work. By the following Friday, the person has begun to fall asleep at around 10 pm, and can wake up at 6 am and feel well-rested. This adaptation to earlier sleep/wake times is known as "advancing the sleep phase." Healthy people can advance their sleep phase by about one hour each day.

Researchers have placed volunteers in caves or special apartments for several weeks without clocks or other time cues. Without time cues, the volunteers tended to go to bed an hour later and to get up about an hour later each day. These experiments appeared to demonstrate that the "free-running" circadian rhythm in humans was about 25 hours long. However, these volunteers were allowed to control artificial lighting and the light in the evening caused a phase delay. More recent research shows that adults of all ages free-run at an average of 24 hours and 11 minutes. To maintain a 24 hour day/night cycle, the biological clock needs regular environmental time cues, e.g. sunrise, sunset, and daily routine. Time cues keep the normal human circadian clock aligned with the rest of the world.

Circadian rhythm abnormalities

Persistent circadian rhythm sleep disorders such as Non-24 hour sleep-wake syndrome are believed to be caused by a reduced ability to reset the sleep/wake cycle in response to environmental time cues. For example, these individuals' circadian clocks might have an unusually long cycle, or might not be sensitive enough to time cues. People with DSPS, which is more common, do entrain to nature's 24 hours, but are unable to sleep and awaken at socially acceptable times, sleeping instead, for example, from 4 a.m. to noon.

See also

A sleep log is a record of an individuals sleeping and waking times, usually over a period of several weeks. ... Zeitgebers are environmental cues that usually help keep the circadian cycle. ... Melatonin, 5-methoxy-N-acetyltryptamine, is a hormone found in all living creatures from algae[1] to humans, at levels that vary in a diurnal cycle. ... Light therapy or phototherapy consists of exposure to specific wavelengths of light using lasers, LEDs, fluorescent lamps, dichroic lamps or very bright, full-spectrum light, for a prescribed amount of time. ... Phase response curve illustrates the relationship between the timing of administration of a sleep phase affecting drug and the effect on the sleep phase. ...


Circadian Rhythm Sleep Disorder on Psychnet-UK

  Results from FactBites:
Delayed sleep phase syndrome - Wikipedia, the free encyclopedia (855 words)
Often, sufferers manage on a few hours sleep a night during the working week, then "catch up" by sleeping excessively at the weekend and sometimes by means of afternoon or evening naps, with inevitable effects on their social lives.
Forcing a patient to go to sleep early, for example by the use of sedatives or "sleeping pills", and forcing early rising does not result in adaptation to the new sleeping pattern.
DSPS is diagnosed by a clinical interview, actigraphic monitoring and/or a sleep log kept by the patient for at least three weeks.
Insomnia Treatments, Treatment For Sleep Disorder, Circadian Rhythm Disorder, Circadian Rhythm Sleep Disorder, Chronic ... (3158 words)
Sleep deprivation and this misalignment of rhythms are two of the most important factors in decreased performance and increased accident rates associated with night work, and may also impact other health consequences of shift work (e.g., digestive and cardiovascular).
These children have a sleep disorder that is debilitating for them and for their families: they sleep in short 'snatches' throughout the day and night, with a complete lack of sleep consolidation.
Sleep disturbances may be caused by an underlying medical (e.g., sleep apnea, arthritis) or psychiatric (e.g., depression) illness.
  More results at FactBites »



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