The Role of Circadian Rhythm Sleep Disorders (CRSD)

A person’s circadian rhythm is an internal biological clock that regulates many physiological systems according to an approximate 24 hour cycle. The key feature of a circadian rhythm disorder is an occasional or continuous disruption in sleep patterns. It is often mistaken for Insomnia, especially if the symptoms persist over a longer period of time; however unlike Insomnia patients, people with CRSD usually get required amount of sleep.

Some of the most common circadian rhythm disorders include:


Advanced Sleep Pattern Syndrome (ASPS) – Is characterized by early sleeping and waking. People with this disorder feel very sleeping  in the early evening hours (6pm-9pm) and wake up early in the morning (3am-6am). Middle-aged adults and the elderly are more likely to suffer from ASPS.

Treatment: Simply delaying sleep time, at a rate of 1 to 3 hours until desired sleep period is achieved should take care of the problem. In more complicated cases Phototherapy (controlled exposure to intense light) may be required.

Delayed Sleep Pattern Syndrome (DSPS) – Contrary to ASPS, people with DSPS have difficulty in initiating sleep and tend to wake up later. It’s most common among adolescents and young adults. People who suffer from this disorder are often perceived as lazy and unmotivated as they do not perform well in the early morning hours. These individuals are most alert and productive late at night.

Treatment: Maintaining regular hours for sleeping and getting up, using an alarm clock or wake up call service. Similar to ADSP treatment adjusting sleep time until desired sleep period is achieved (ideally 11:00pm- 7am) and bright light therapy may be useful.

Jet Lag– Crossing between two or more time zones can create a conflict between person’s circadian rhythm timing and that of a new time zone. Symptoms, including fatigue and insomnia, are only temporary and usually disappear completely within a week.

Shift Work Disorder– People who work irregular hours (e.g. Truck drivers) or work at night are at bigger risk to suffer from shift work disorder which is often characterized by complaints of insomnia or excessive sleepiness.

Treatment: Some patients find medication to be helpful, antidepressants, which are used in treatment of various sleep disorders are known to positively affect and sometimes readjust circadian rhythm.



The Sleep Blog does not provide medical advice, diagnosis, or treatment. Instead, this website provides general information for educational purposes only. Always seek the advice of a qualified health care provider if you have questions or concerns regarding any medical condition or treatment.

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