Circadian Rhythm Sleep Disorder

Persistent or recurrent pattern of sleep disruption leading to excessive sleepiness or insomnia, that is due to a mis-matching between the sleep/wake schedule required by a person's environment and their circadian sleep-wake pattern. (Circadian is from a Latin word meaning "daily".) The sleep disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning. The disturbance does not occur exclusively during the course of another Sleep Disorder or other mental disorder and the disturbance is not due to the direct physiological effects of a substance.

General characteristics are:

1. There is a persisting or repeating mismatch between a person's sleep-wake pattern and the sleep-wake demands of that patient's environment. The mismatch leads to excessive insomnia or sleepiness.
2. This problem causes clinically important distress or impairs work or social life.
3. It doesn't occur solely during another mental disorder or Sleep Disorder.
4. It is not directly caused by a general medical condition or substance use, including medications and drugs of abuse.

Types include:

Delayed Sleep Phase Type. The patient repeatedly has trouble getting to sleep and trouble awakening on time. People with this disorder are often misunderstood as irresponsible and lazy.

Jet Lag Type. Alertness and sleepiness occur at inconvenient times of day after traveling across more than one time zone. People who are ordinarily early risers are particularly vulnerable.

Shift Work Type. Because of night shift work or frequently changing job shifts, the patient experiences excessive sleepiness during major periods of wakefulness or insomnia during major sleep period. As with jet lag, shift-work CRSD is more likely to strike people who are typically early risers than night owls.

Other symptoms include depression, hyperactivity, and erratic or antisocial behavior.

Cause

Circadian Rhythm Sleep Disorder causes periods of insomnia or sleepiness, depending on the time of day and how much time the person has to make up for the insomnia. Only in severe cases of disruption would a person with this type of difficulty seek treatment. The relative normalcy of this disorder is indicated by its subtypes, which include "shift work type" and "jet lag type," along with "delayed sleep phase" and "unspecified" types. Difficulties with adapting to changing work shifts and jet trips are so universal that they hardly deserve to be called disorders, and are so classified only if they cause significant distress or impairment, as with all disorders.

Treatment

Bright light treatment and melatonin can be used to treat this disorder, as well as hypnotics. One problem for doctors is in understanding the specifics of the circadian cycle in any individual patient. While researchers can do studies which measure body temperature and melatonin levels, the typical doctor has no access to such knowledge, and must often guess when prescribing the timing of the light exposure and melatonin supplements.

Sleep Disorders

Dyssomnias

Parsomnias