DSM-IV

In DSM-IV, this disorder is called Primary Hypersomnia

Diagnostic Criteria

A. The predominant complaint is excessive for at least 1 month (or less if recurrent) as evidenced by either prolonged sleep episodes or daytime sleep episodes that occur almost daily.

B. The excessive sleepiness causes clinically significant distress or impairment in social, occupational or other important areas of functioning.

C. The excessive sleepiness is not better accounted for by insomnia and does not occur exclusively during the course of another Sleep Disorder (e.g., Narcolepsy, Breathing-Related Sleep Disorder, Circadian Rhythm Sleep Disorder, or a Parasomnia) and cannot be accounted for by an inadequate amount of sleep.

D. The disturbance does not occur exclusively during the course of another mental disorder.

E. 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.

Specify if:

  • Recurrent: if there are periods of excessive sleepiness that last at least 3 days occurring several times a year for at least 2 years

Specifier

Recurrent

This specifier is used if there are periods of excessive sleepiness that last at least 3 days occurring several times a year for at least 2 years.

Most individuals with Primary Hypersomnia have consistent and persistent symptoms. In contrast, the Recurrent form should be noted if symptoms occur periodically for several days to several weeks, with symptomatic periods recurring several times per year. Between periods of excessive sleepiness, sleep duration and daytime alertness are normal. In the recurrent form of Primary Hypersomnia known as Kleine-Levin syndrome, individuals may spend 18-20 hours asleep or in bed. The recurrent periods of sleepiness are associated with other characteristics clinical features indicating disinhibition. Indiscriminate hypersexuality including inappropriate sexual advances and overt masturbation can be seen in males (and less often in females). Compulsive overeating with acute weight gain may occur. Irritability, depersonalization, depression, confusion, and occasional hallucinations have been described in some individuals, and impulsive behaviors can also occur. Other recurrent forms of hypersomnia can be seen in the absence of these features. For instance, some females report regularly occurring periods of hypersomnia at specific times of their menstrual cycle.

Differential Diagnosis

Long sleepers

"Normal" sleep duration varies considerably in the general population. "Long sleepers" (i.e., individuals who require a greater than average amount of sleep) do not have excessive daytime sleepiness, sleep drunkenness, or automatic behavior when they obtain their required amount of nocturnal sleep. If social or occupational demands lead to shorter nocturnal sleep, daytime symptoms may appear. In Primary Hypersomnia, by contrast, symptoms of excessive sleepiness occur regardless of nocturnal sleep duration.

Inadequate amount of nocturnal sleep

An inadequate amount of nocturnal sleep can produce symptoms of daytime sleepiness very similar to those of Primary Hypersomnia. An average sleep duration of fewer than 7 hours per night strongly suggests inadequate nocturnal sleep, and an average of more than 9 hours of sleep per 24-hour period suggests Primary Hypersomnia. Individuals with inadequate nocturnal sleep typically "catch up" with longer sleep durations on days when they are free from social or occupational demands or on vacations. Unlike Primary Hypersomnia, insufficient nocturnal sleep is unlikely to persist unabated for decades. A diagnosis of Primary Hypersomnia should not be made if there is a question regarding the adequacy of nocturnal sleep duration. A diagnostic and therapeutic trial of sleep extension for 10-14 days can often clarify the diagnosis.

Primary Insomnia

Daytime sleepiness, which is a characteristic feature of Primary Hypersomnia, can also occur in Primary Insomnia, but the sleepiness is less severe in individuals with Primary Insomnia. When daytime sleepiness is judged to be due to insomnia, an additional diagnosis of Primary Hypersomnia is not given.

Narcolepsy

Primary Hypersomnia and Narcolepsy are similar with respect to the degree of daytime sleepiness, age at onset, and stable course over time, but can be distinguished based on distinctive clinical and laboratory features. Individuals with Primary Hypersomnia typically have longer and less disrupted nocturnal sleep, greater difficulty awakening, more persistent daytime sleepiness (as opposed to more discrete "sleep attacks" in Narcolepsy), longer and less refreshing daytime sleep episodes, and little or no dreaming during daytime naps. By contrast, individuals with Narcolepsy have cataplexy and recurrent intrusions of elements of REM sleep into the transition between sleep and wakefulness (e.g., sleep-related hallucinations and sleep paralysis). The MSLT typically demonstrates shorter sleep latencies (i.e., greater physiological sleepiness) as well as the presence of multiple sleep-onset REM periods in individuals with Narcolepsy.

Breathing-Related Sleep Disorder

Individuals with Primary Hypersomnia and Breathing-Related Sleep Disorder may have similar patterns of excessive sleepiness. Breathing-Related Sleep Disorder is suggested by a history of loud snoring, pauses in breathing during sleep, brain injury, or cardiovascular disease and by the presence of obesity, oropharyngeal anatomical abnormalities, hypertension, or heart failure on physical examination. Polysomnographic studies can confirm the presence of apneic events in Breathing-Related Sleep Disorder (and their absence in Primary Hypersomnia).

Circadian Rhythm Sleep Disorder and Parasomnias

Circadian Rhythm Sleep Disorder is often characterized by daytime sleepiness. A history of an abnormal sleep-wake schedule (with shifted or irregular hours) is present in individuals with Circadian Rhythm Sleep Disorder. Parasomnias rarely produce the prolonged, undisturbed nocturnal sleep or daytime sleepiness characteristic of Primary Hypersomnia.

Other mental disorders

Primary Hypersomnia must be distinguished from mental disorders that include hypersomnia as an essential or associated feature. In particular, complaints of daytime sleepiness may occur in a Major Depressive Episode, With Atypical Features, and in the depressed phase of Bipolar Disorder. The diagnosis of Primary Hypersomnia is not given if hypersomnia occurs exclusively during the course of another mental disorder. A thorough investigation for the presence of other mental disorders is essential before considering the diagnosis of Primary Hypersomnia. A diagnosis of Primary Hypersomnia can be made in the presence of another current or past mental disorder if the mental disorder is judged to not account for the hypersomnia or if the hypersomnia and the mental disorder have an independent course (e.g., in an individual with chronic hypersomnia who alter develops a Major Depressive Disorder). In contrast, when hypersomnia occurs as a manifestation of, and exclusively during the course of, another mental disorder, the diagnosis of Hypersomnia Related to Another Mental Disorder may be more appropriate. This diagnosis should only be considered when the hypersomnia is the predominant complaint and is sufficiently severe to warrant independent clinical attention; otherwise, no separate diagnosis is necessary.

Sleep Disorder Due to a General Medical Condition and Substance-Induced Sleep Disorder

Primary Hypersomnia must be distinguished from Sleep Disorder Due to a General Medical Condition, Hypersomnia Type. The diagnosis is Sleep Disorder Due to a General Medical Condition when the hypersomnia is judged to be a direct physiological consequence of a specific general medical condition (e.g., brain tumor). This determination is based on history, laboratory findings, or physical examination. Substance-Induced Sleep Disorder, Hypersomnia Type, is distinguished from Primary Hypersomnia by the fact that a substance (i.e., a drug of abuse, a medication, or exposure to a toxin) is judged to be etiologically related to the hypersomnia. For example, hypersomnia occurring only in the context of withdrawal from cocaine would be diagnosed as Cocaine-Induced Sleep Disorder, Hypersomnia Type, With Onset During Withdrawal.

DSM-5

Diagnostic Criteria

A. Self-reported excessive sleepiness (hypersomnolence) despite a main sleep period lasting at least 7 hours, with at least one of the following symptoms:

  1. Recurrent periods of sleep or lapses into sleep within the same day.
  2. A prolonged main sleep episode of more than 9 hours per day that is nonrestorative (i.e., unrefreshing).
  3. Difficulty being fully awake after abrupt awakening.

B. The hypersomnolence occurs at least three times per week, for at least 3 months.

C. The hypersomnolence is accompanied by significant distress or impairment in cognitive, social, occupational, or other important areas of functioning.

D. The hypersomnolence is not better explained by and does not occur exclusively during the course of another sleep disorder (e.g., narcolepsy, breathing-related sleep disorder, circadian rhythm sleep-wake disorder, or a parasomnia).

E. The hypersomnolence is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication).

F. Coexisting mental and medical disorders do not adequate explain the predominant complaint of hypersomnolence.

Specify if:

  • With mental disorder, including substance use disorders
  • With medical condition
  • With another sleep disorder

Note: Record also the relevant associated mental disorder, medical condition, or other sleep disorder immediately after the code for hypersomnolence disorder in order to indicate the association.

Specify if:

  • Acute: Duration of less than 1 month.
  • Subacute: Duration of 1-3 months.
  • Persistent: Duration of more than 3 months.

Specify current severity:

Specify severity based on degree of difficulty maintaining daytime alertness as manifested by the occurrence of multiple attacks of irresistible sleepiness within any given day occurring, for example, while sedentary, driving, visiting with friends, or working.

  • Mild: Difficulty maintaining daytime alertness 1-2 days/week.
  • Moderate: Difficulty maintaining daytime alertness 3-4 days/week.
  • Severe: Difficulty maintaining daytime alertness 5-7 days/week.

Differential Diagnosis

Normative variation in sleep

"Normal" sleep duration varies considerably in the general population. "Long sleepers" (i.e., individuals who require a greater than average amount of sleep) do not have excessive sleepiness, sleep inertia, or autonomic behavior when they obtain their required amount of nocturnal sleep. Sleep is reported to be refreshing. If social or occupational demands lead to shorter nocturnal sleep, daytime symptoms may appear. In hypersomnolence disorder, by contrast, symptoms of excessive sleepiness occur regardless of nocturnal sleep duration. An inadequate amount of nocturnal sleep, or behaviorally induced insufficient sleep syndrome, can produce symptoms of daytime sleepiness very similar to those of hypersomnolence. An average sleep duration of fewer than 7 hours per night strongly suggests inadequate nocturnal sleep, and an average of more than 9-10 hours of sleep per 24-hour period suggests hypersomnolence. Individuals with inadequate nocturnal sleep typically "catch up" with longer sleep durations on days when they are free from social or occupational demands or on vacations. Unlike hypersomnolence, insufficient nocturnal sleep is unlikely to persist unabated for decades. A diagnosis of hypersomnolence disorder should not be made if there is a question regarding the adequacy of nocturnal sleep duration. A diagnostic and therapeutic trial of sleep extension for 10-14 days can often clarify the diagnosis.

Poor sleep quality and fatigue

Hypersomnolence disorder should be distinguished from excessive sleepiness related to insufficient sleep quantity or quality and fatigue (i.e., tiredness not necessarily relieved by increased sleep and unrelated to sleep quantity or quality). Excessive sleepiness and fatigue are difficult to differentiate and may overlap considerably.

Breathing-related sleep disorders

Individuals with hypersomnolence and breathing-related sleep disorders may have similar patterns of excessive sleepiness. Breathing-related sleep disorders are suggested by a history of loud snoring, pauses in breathing during sleep, brain injury, or cardiovascular disease and by the presence of obesity, oropharyngeal anatomical abnormalities, hypertension, or heart failure on physical examination. Polysomnographic studies can confirm the presence of apneic events in breathing-related sleep disorder (and their absence in hypersomnolence disorder).

Circadian rhythm sleep-wake disorders

Circadian rhythm sleep-wake disorders are often characterized by daytime sleepiness. A history of an abnormal sleep-wake schedule (with shifted or irregular hours) is present in individuals with a circadian rhythm sleep-wake disorder.

Parasomnias

Parasomnias rarely produce the prolonged, undisturbed nocturnal sleep or daytime sleepiness characteristic of hypersomnolence disorder.

Other mental disorders

Hypersomnlence disorder must be distinguished from mental disorders that include hypersomnolence as an essential or associated feature. In particular, complaints of daytime sleepiness may occur in a major depressive episode, with atypical features, and in the depressed phase of bipolar disorder. Assessment for other mental disorders is essential before a diagnosis of hypersomnolence disorder is considered. A diagnosis of hypersomnolence disorder can be made in the presence of another current or past mental disorder.

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