- 1 DSM-IV
- 1.1 Diagnostic Criteria
- 1.2 Subtypes
- 1.3 Differential Diagnosis
- 2 DSM-5
- 2.1 Diagnostic Criteria
- 2.2 Delayed Sleep Phase Type
- 2.3 Advanced Sleep Phase Type
- 2.4 Irregular Sleep-Wake Type
- 2.5 Non-24-Hour Sleep-Wake Type
- 2.6 Shift Work Type
In DSM-IV, this disorder is called Circadian Rhythm Sleep Disorder
A. A persistent or recurrent pattern of sleep disruption leading to excessive sleepiness or insomnia that is due to a mismatch between the sleep-wake schedule required by a person's environment and his or her circadian sleep-wake pattern.
B. The sleep disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
C. The disturbance does not occur exclusively during the course of another Sleep Disorder or other mental disorder.
D. The disturbance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.
- Delayed Sleep Phase Type: a persistent pattern of late sleep onset and late awakening times, with an inability to fall asleep and awaken at a desired earlier time
- Jet Lag Type: sleepiness and alertness that occur at an inappropriate time of day relative to local time, occurring after repeated travel across more than one time zone
- Shift Work Type: insomnia during the major sleep period or excessive sleepiness during the major awake period associated with night shift work or frequently changing shift work
- Unspecified Type
Delayed Sleep Phase Type
This type of Circadian Rhythm Sleep Disorder results from an endogenous sleep-wake cycle that is delayed relative to the demands of society. Measurement of endogenous circadian rhythms (e.g., core body temperature) reflects this delay. Individuals with this subtype ("night owls") are hypothesized to have an abnormally diminished ability to phase-advance sleep-wake hours (i.e., to move sleep and wakefulness to earlier clock times). As a result, these individuals are "locked in" to habitually late sleep hours and cannot move these sleep hours forward to an earlier time. The circadian phase of sleep is stable: individuals will fall asleep and awaken at consistent, albeit delayed, times when left to their own schedule (e.g., on weekends or vacations). Affected individuals complain of difficulty falling asleep at socially acceptable hours, but once sleep is initiated, it is normal. There is concomitant difficulty awakening at socially acceptable hours (e.g., multiple alarm clocks are often unable to arouse the individual). Because many individuals with this disorder will be chronically sleep deprived, sleepiness during the desired wake period may occur.
Jet Lag Type
In this type of Circadian Rhythm Sleep Disorder, the endogenous circadian sleep-wake cycle is normal and the disturbance arises from conflict between the pattern of sleep and wakefulness generated by the circadian system and the pattern of sleep and wakefulness required by a new time zone. Individuals with this type complain of a mismatch between desired and required hours of sleep and wakefulness. The severity of the mismatch is proportional to the number of time zones traveled through, with maximal difficulties often noted after traveling through eight or more time zones in less than 24 hours. Eastward travel (advancing sleep-wake hours) is typically more difficult for most individuals to tolerate than westward travel (delaying sleep-wake hours).
Shift Work Type
In this type of Circadian Rhythm Sleep Disorder, the endogenous circadian sleep-wake cycle is normal and the disturbance arises from conflict between the pattern of sleep and wakefulness generated by the circadian system and the desired pattern of sleep and wakefulness required by shift work. Rotating-shift schedules are the most disruptive because they force sleep and wakefulness into aberrant circadian positions and prevent any consistent adjustment. Night- and rotating-shift workers typically have a shorter sleep duration and more frequent disturbances in sleep continuity than morning and afternoon workers. Conversely, there may also be sleepiness during the desired wake period, that is, in the middle of the night work shift. The circadian mismatch of the Shift Work Type is further exacerbated by insufficient sleep time, social and family demands, and environmental disturbances (e.g., telephone, traffic noise) during intended sleep times.
This type of Circadian Rhythm Sleep Disorder should be indicated if another pattern of circadian sleep disturbance (e.g., advanced sleep phase, non-24-hours sleep-wake pattern, or irregular sleep-wake pattern) is present. An "advanced sleep phase pattern" is the analog of Delayed Sleep Phase Type, but in the opposite direction: individuals complain of an inability to stay awake in the evening and spontaneous awakening in the early morning hours. "Non-24-hour sleep-wake pattern" denotes a free-running cycle: the sleep-wake schedule follows the endogenous circadian rhythm period of approximately 24-25 hours despite the presence of 24-hour time cues in the environment. In contrast to the stable sleep-wake pattern of the Delayed or advanced sleep phase types, these individuals' sleep-wake schedules become progressively delayed relative to the 24-hour clock, resulting in a changing sleep-wake pattern over successful days. "Irregular sleep-wake pattern" indicates the absence of an identifiable pattern of sleep and wakefulness.
Normal patterns of sleep
Circadian Rhythm Sleep Disorder must be distinguished from normal patterns of sleep and normal adjustments following a change in schedule. They key to such distinctions lies in the persistence of the disturbance and the presence and degree of social or occupational impairment. For instance, many adolescents and young adults maintain delayed sleep-wake schedules, but without distress or interference with school or work routines. Almost anyone who travels across time zones will experience transient sleep disruption. The diagnosis of the Jet Lag Type should be reserved for an individual with frequent travel requirements and associated severe sleep disturbances and work disruption.
Volitional patterns of delayed sleep hours
Delayed Sleep Phase Type must be differentiated from volitional patterns of delayed sleep hours. Some individuals who voluntarily delay sleep onset to participate in social or work activities may complain of difficulty awakening. When permitted to do so, these individuals fall asleep readily at earlier times and, after a period of recovery sleep, have no significant difficulty awakening in the morning. In such cases, the primary problem is sleep deprivation rather than a Circadian Rhythm Sleep Disorder. Other individuals (particularly children and adolescents) may volitionally shift sleep hours to avoid school or family demands. The pattern of difficulty awakening vanishes when desired activities are scheduled in the morning hours. In a similar way, younger children involved in limit-setting battles with parents may present as having Delayed Sleep Phase Type.
Jet Lag and Shift Work Types must be distinguished mainly from other primary Sleep Disorders, such as Primary Insomnia and Primary Hypersomnia. The history of jet lag or shift work, with undisturbed sleep on other schedules, usually provides sufficient evidence to exclude these other disorders. In some cases, other primary Sleep Disorders, such as Breathing-Related Sleep Disorder or periodically limb movements during sleep, may complicate Shift Work or Jet Lag Types. This possibility should be suspected when reversion to a normal diurnal schedule does not provide relief from sleep-related symptoms. Other types of circadian Rhythm Sleep Disorder, such as "non-24-hour sleep-wake pattern" and "irregular sleep-wake pattern," are distinguished from the Delayed Sleep Phase Type by the stably delayed sleep-wake hours characteristic of the latter.
Other mental disorders
Patterns of delayed or advanced sleep that occur exclusively during another mental disorder are not diagnosed separately (e.g., a pattern of early morning awakening in Major Depressive Disorder or a pattern of delayed sleep in Schizophrenia).
Substances (including medications) can cause delayed sleep onset or awakening in the morning. For instance, consumption of caffeine or nicotine in the evening may delay sleep onset, and the use of hypnotic medications in the middle of the night may delay the time of awakening. A diagnosis of Substance-Induced Sleep Disorder may be considered if the sleep disturbance is judged to be a direct physiological consequence of regular substance use and warrants independent clinical attention. General medical conditions rarely cause fixed delays or advances of the sleep-wake schedule and typically pose no difficulty in differential diagnosis.
A. A persistent recurrent pattern of sleep disruption that is primarily due to an alteration of the circadian system or to a misalignment between the endogenous circadian rhythm and the sleep-wake schedule required by an individual's physical environment or social or professional schedule.
B. The sleep disruption leads to excessive sleepiness or insomnia, or both.
C. The sleep disturbance causes clinically significant distress or impairment in social, occupational, and other important areas of functioning.
- Delayed sleep phase type: A pattern of delayed sleep onset and awakening times, with an inability to fall asleep and awaken at a desired or conventionally acceptable earlier time.
- Specify if:
- Familial: A family history of delayed sleep phase is present.
- Specify if:
- Overlapping with non-24-hour sleep-wake type: Delayed sleep phase type may overlap with another circadian rhythm sleep-wake disorder, non-24-hour sleep-wake type.
- Specify if:
- Advanced sleep phase type: A pattern of advanced sleep onset and awakening times, with inability to remain awake or asleep until the desired or conventionally acceptable later sleep or wake times.
- Specify if:
- Familial: A family history of advanced sleep phase is present.
- Specify if:
- Irregular sleep-wake type: A temporally disorganized sleep-wake pattern, such that the timing of sleep wake periods is variable throughout the 24-hour period.
- Non-24-hour sleep-wake type: A pattern of sleep-wake cycles that is not synchronized to the 24-hour environment, with a consistent daily drift (usually to later and later times) of sleep onset and wake times.
- Shift work type: Insomnia during the major sleep period and/or excessive sleepiness (including inadvertent sleep) during the major awake period associated with a shift work schedule (i.e., requiring unconventional work hours).
- Unspecified type
- Episodic: Symptoms last at least 1 month but less than 3 months.
- Persistent: Symptoms last 3 months or longer.
- Recurrent: Two or more episodes occur within the space of 1 year.
Delayed Sleep Phase Type
Normative variations in sleep
Delayed sleep phase type must be distinguished from "normal" sleep patterns in which an individual has a late schedule that does not cause personal, social, or occupational distress (most commonly seen in adolescents and young adults).
Insomnia disorder and other circadian rhythm sleep-wake disorders should be included in the differential. Excessive sleepiness may also be caused by other sleep disturbances, such as breathing-related sleep disorders, insomnias, sleep-related movement disorders, and medical, neurological, and mental disorders. Overnight polysomnography may help in evaluating for other comorbid sleep disorders, such as sleep apnea. The circadian nature of delayed sleep phase type, however, should differentiate it from other disorders with similar complaints.
Advanced Sleep Phase Type
Advances sleep phase type may be documented with the specified "familial." Although the prevalence of familial advanced sleep phase type has not been established, a family history of advanced sleep phase is present in individuals with advanced sleep phase type. In this type, specific mutations demonstrate an autosomal dominant mode of inheritance. In the familial form, onset of symptoms may occur earlier (during childhood and early adulthood), the course is persistent, and the severity of symptoms may increase with age.
Behavioral factors such as irregular sleep schedules, voluntary early awakening, and exposure to light in the early morning should be considered, particularly in older adults. Careful attention should be paid to rule out other sleep-wake disorders, such as insomnia disorder, and other mental disorders and medical conditions that can causes early morning awakening.
Because early morning awakening, fatigue, and sleepiness are prominent features of major depressive disorder, depressive and bipolar disorders must also be considered.
Irregular Sleep-Wake Type
Normative variations in sleep
Irregular sleep-wake type should be distinguished from a voluntary irregular sleep-wake schedule and poor sleep hygiene, which can result in insomnia and excessive sleepiness.
Other medical conditions and mental disorders
Other causes of insomnia and daytime sleepiness, including comorbid medical conditions and mental disorders or medication, should be considered.
Non-24-Hour Sleep-Wake Type
Circadian rhythm sleep-wake disorders
In sighted individuals, non-24-hour sleep-wake type should be differentiated from delayed sleep phase type, as individuals with delayed sleep phase type may display a similar progressive delay in sleep period for several days.
Depressive symptoms and depressive disorders may result in similar circadian dysregulation and symptoms.
Shift Work Type
Normative variations in sleep with shift work
The diagnosis of shift work type, as opposed to the "normal" difficulties of shift work, must depend to some extent on the severity of symptoms and/or level of distress experienced by the individual. Presence of shift work type symptoms even when the individual is able to live on a day-oriented routine for several weeks at a time may suggest the presence of other sleep disorders, such as sleep apnea, insomnia, and narcolepsy, which should be ruled out.