Type Characteristic
Sleep-onset insomnia (initial insomnia) Difficulty initiating sleep at bedtime
Sleep maintenance insomnia (middle insomnia) Difficulty maintaining sleep, characterized by frequent or prolonged awakenings throughout the night
Late insomnia Early-morning awakening with an inability to return to sleep
acute insomnia
Condition lasting a few days to a few weeks, often associated with life events or changes in sleep schedules
Duration Characteristic
Episodic Symptoms lasting ≥1 month but <3mos
Persistent Symptoms lasting ≥3mos
Recurrent Two or more episodes within a 1yr period
Acute and short-term Symptoms lasting <3mos but meets all criteria with regard to frequency, intensity, distress, and/or impairment
Excessive sleepiness despite a main sleep period lasting at least 7hrs, with one of the following:

• Recurrent periods of sleep or lapses into sleep within the same day

• Prolonged main sleep episode of >9hrs/day that is nonrestorative

• Difficulty being fully awake after abrupt awakening

Severity Characteristic
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
Duration Characteristic
Acute Symptoms lasting <1 month
Subacute Symptoms lasting 1−3mos
Persistent Symptoms lasting >3mos
Recurrent periods of irrepressible need to sleep, lapsing into sleep, or napping within the same day, at least 3 times/week over 3mos, with at least one of the following:

• Episodes of cataplexy at least a few times/month

—In long-standing disease: brief episodes of bilateral loss of muscle tone with maintained consciousness, precipitated by laughter or joking

—In children or recent-onset (within 6mos): spontaneous grimaces or episodes of jaw-opening with tongue thrusting or global hypotonia, without any obvious emotional triggers

• Hypocretin deficiency

• Rapid eye movement (REM) sleep latency ≤15mins in nocturnal sleep polysomnography or mean sleep latency ≤8mins and ≥2 sleep-onset REM periods in multiple sleep latency test

Severity Characteristic
Mild Cataplexy less than once per week, need for naps only 1−2 times/day, and less disturbed nocturnal sleep
Moderate Cataplexy once daily or every few days, disturbed nocturnal sleep, and need for multiple naps daily
Severe Drug-resistant cataplexy with multiple attacks daily, nearly constant sleepiness, and disturbed nocturnal sleep (eg, movements, insomnia, vivid dreams)
Type Characteristic
Delayed sleep phase Pattern of delayed sleep onset and awakening times, with inability to fall asleep and awaken at a desired or conventional acceptable earlier time
Advanced sleep phase Pattern of advanced sleep onset and awakening times, with inability to remain awake or asleep until the desired or conventional acceptable later sleep or wake times
Irregular sleep-wake Temporally disorganized sleep-wake pattern, with variable timing of sleep and wake periods throughout the 24-hr period (primarily insomnia at night and excessive sleepiness during the day)
Non-24-hour sleep-wake Pattern of sleep-wake cycles unsynchronized to the 24-hr environment, with a consistent daily drift of sleep onset and wake times
Shift work Insomnia during the major sleep period and/or excessive sleepiness during the major awake period associated with a shift work schedule (unconventional work hours)
Duration Characteristic
Episodic Symptoms lasting ≥1 month but <3mos
Persistent Symptoms lasting ≥3mos
Recurrent Two or more episodes within a 1yr period

• Prominent and severe disturbance in sleep during or soon after substance intoxication or after withdrawal from or exposure to a medication capable of producing such symptoms

• Substances/medications: alcohol, caffeine, cannabis, opioids, sedatives/hypnotics, anxiolytics, stimulants (eg, cocaine, amphetamines), tobacco, others (drugs that affect central or autonomic nervous systems)

Type Characteristic
Insomnia Difficulty falling asleep or maintaining sleep, frequent nocturnal awakenings, or nonrestorative sleep
Daytime sleepiness Excessive sleepiness/fatigue during waking hours or, less commonly, long sleep period
Parasomnia Abnormal behavioral events during sleep
Mixed Substance/medication-induced sleep problem characterized by multiple types of sleep symptoms, with no clear predominating symptom

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Arlington, VA, American Psychiatric Association, 2013.

(Rev. 4/2018)

This article originally appeared on MPR