Circadian Rhythm Sleep Disorder

Circadian Rhythm Sleep Disorder is a mismatch between a person's internal sleep-wake cycle and external demands. ("Circadian" is a combination of the Latin "circa," or about, and "dia" or day.). 

In a sense, it is not a disorder, because there is nothing unusual about the person, except perhaps more than normal difficulty in shifting the cycle of sleep and waking. Nevertheless, the mismatch creates periods of insomnia, sleepiness, or both, 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. 

The delayed sleep phase disorder is diagnosed when an individual is unable to adjust to the usual sleep pattern, and stays up late and sleeps late despite attempts to adjust. The attempts to adjust may result in too little sleep and consequent daytime sleepiness. 

Sleep disorder clinics offer programs for circadian disorders, as well as for the other types of sleep disorders.

Visit a useful site maintained by Stanford University that offers detailed information on sleep disorders and access to a wealth of other information.

                                                                                                                                Last updated  12/19/03