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. 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:
There is a persisting or repeating mismatch between a person's
sleep-wake pattern and the sleep-wake demands of that patient's
The mismatch leads to excessive insomnia or sleepiness.
This problem causes clinically important distress or impairs work
or social life.
It doesn't occur solely during another mental disorder or Sleep
It is not directly caused by a general medical condition or substance
use, including medications and drugs of abuse.
Delayed Sleep Phase Type. The patient repeatedly
has trouble getting to sleep and trouble awakening on time.
Jet Lag Type. Alertness and sleepiness occur
at inconvenient times of day after traveling across more than
one time zone.
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.
Some disorders display similar or sometimes even the same symptom.
The clinician, therefore, in his diagnostic attempt, has to differentiate
against the following disorders which one needs to be ruled out
to establish a precise diagnosis.
Rhythm Sleep Disorder causes 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.