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For further information, see CMDT Part 25-15: Sleep-Wake Disorders

Key Features

Essentials of Diagnosis

  • Transient episodes are usually of little significance

  • Common factors

    • Stress

    • Caffeine

    • Physical discomfort

    • Daytime napping, early bedtime

  • Psychiatric disorders are often associated with persistent insomnia

General Considerations

  • Sleep consists of two distinct states

    • REM (rapid eye movement) sleep, also called dream sleep

    • NREM (non-REM) sleep, is divided into stages 1, 2, 3, and 4

    • Dreaming occurs mostly in REM and to a lesser extent in NREM sleep

    • Sleep is a cyclic phenomenon, with four or five REM periods during the night accounting for about one-fourth of the total night's sleep (1½–2 hours)

    • The first REM period occurs about 80–120 minutes after onset of sleep and lasts about 10 minutes

    • Later REM periods are longer (15–40 minutes) and occur mostly in the last hours of sleep. Most stage 4 (deepest) sleep occurs in the first several hours

  • Age-related changes in normal sleep include

    • An unchanging percentage of REM sleep

    • A marked decrease in stage 3 and stage 4 sleep

    • An increase in wakeful periods during the night

    • These normal changes, early bedtimes, and daytime naps contribute to the insomnia in older people

    • Variations in sleep patterns may be due to circumstances (eg, "jet lag") or to idiosyncratic patterns ("night owls") in persons with different "biological rhythms" who habitually go to bed late and sleep late in the morning

    • Loss of sleep impairs creativity and rapidity of response to unfamiliar situations

    • Desynchronization sleep disorder: rare; chronic difficulty in adapting to a 24-hour sleep-wake cycle; can be resynchronized by altering exposure to light

  • Depression is usually associated with

    • Fragmented sleep

    • Decreased total sleep time

    • Earlier onset of REM sleep

    • A shift of REM activity to the first half of the night

    • Loss of slow-wave sleep

  • Manic disorders

    • Sleeplessness is a cardinal feature and an important early sign of impending mania in bipolar cases

    • Total sleep time is decreased

    • Shortened REM latency and increased REM activity

  • Sleep-related panic attacks occur in the transition from stage 2 to stage 3 sleep in some patients with a longer REM latency in the sleep pattern preceding the attacks

  • Alcohol abuse

    • May cause or be secondary to the sleep disturbance

    • There is a tendency to use alcohol as a means of getting to sleep without realizing that it disrupts the normal sleep cycle

    • Acute alcohol intake

      • Produces a decreased sleep latency with reduced REM sleep during the first half of the night

      • REM sleep is increased in the second half of the night, with an increase in total amount of slow-wave sleep (stages 3 and 4)

      • Vivid dreams and frequent awakenings are common

    • Chronic alcohol abuse

      • Increases stage 1 and decreases REM sleep (most drugs delay or block REM sleep)

      • Symptoms persist for many months after the person has stopped drinking

    • Acute alcohol or other sedative withdrawal

      • Delayed onset of ...

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