Non-REM Parasomnias (Non-REM Sleep Arousal Disorders)

Primer

Non-Rapid Eye Movement (NREM) Parasomnias (ICSD-3), also referred to as NREM Sleep Arousal Disorders (DSM-5) includes sleepwalking and sleep terrors (night terrors). Both of these conditions consist of repeated occurrence of incomplete arousals, usually beginning during the first third of the major sleep episode, that typically are brief, lasting 1-10 minutes, but may be protracted, lasting up to 1 hour. The maximum duration of an event is unknown. The eyes are typically open during these events.

Prevalence

Isolated or infrequent NREM sleep arousal disorders are very common in the general population. The most common non-rapid eye movement (NREM) parasomnias in children are the disorders of arousal (e.g., sleepwalking, night terrors, and confusional arousals), which occur most commonly in the first half of the night.

DSM-5 Diagnostic Criteria

Criterion A

Recurrent episodes of incomplete awakening from sleep, usually occurring during the first third of the major sleep episode, accompanied by either one of the following:

  1. Sleepwalking: Repeated episodes of rising from bed during sleep and walking about. While sleepwalking, the individual has a blank, staring face; is relatively un responsive to the efforts of others to communicate with him or her; and can be awakened only with great difficulty.
    See main article: Sleepwalking
  2. Sleep terrors: Recurrent episodes of abrupt terror arousals from sleep, usually beginning with a panicky scream. There is intense fear and signs of autonomic arousal, such as mydriasis, tachycardia, rapid breathing, and sweating, during each episode. There is relative unresponsiveness to efforts of others to comfort the individual during the episodes.
    See main article: Sleep Terrors (Night Terrors)
Criterion B

No or little (e.g., only a single visual scene) dream imagery is recalled.

Criterion C

Amnesia for the episodes is present.

Criterion D

The episodes cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

Criterion E

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

Criterion F

Co-existing mental and medical disorders do not explain the episodes of sleepwalking or sleep terrors.

Specifiers

Specifiers

Specify if:

  • Sleepwalking type
    • With sleep-related eating
    • sleep-related sexual behavior (sexsomnia)
  • Sleep terror type

Pathophysiology

Many individuals exhibit both subtypes of arousals (sleepwalking and night terrors) on different occasions, which suggests a unifying underlying pathophysiology. Sleepwalking and night terrors reflect varying degrees of simultaneous occurrence of wakefulness and NREM sleep, resulting in complex behaviours arising from sleep with varying degrees of conscious awareness, motor activity, and autonomic activation.

Differential Diagnosis

  • Nightmare disorder
  • Breathing-related sleep disorders
  • REM sleep behaviour disorder
  • Parasomnia overlap syndrome
  • Sleep-related seizures
  • Alcohol-induced blackouts
  • Dissociative amnesia, with dissociative fugue
  • Malingering or other voluntary behaviour occurring during wakefulness
  • Panic disorder
  • Medication-induced complex behaviours
  • Night eating syndrome

Comparison of Parasomnias

Mnemonic

You can REMember events (i.e. - no confusion, no amnesia) in REM parasomnias!

Comparison of Parasomnias

Parasomnia Type Stage of Arousal Time of Night EEG during event EMG during event Unresponsive during event Autonomic activity Anmesia Confusion post-episode Family history of parasomnias
Confusional Arousal NREM NREM Stage 2-4 Anytime N/A Low Yes Low Yes Yes Yes
Sleepwalking NREM NREM Stage 3-4 First 2 hours Mixed Low Yes Low Yes Yes Yes
Sleep terrors NREM NREM Stage 3-4 First 2 hours Mixed Low Yes High Yes Yes Yes
REM sleep behaviour disorder REM REM Anytime (but more likely later half) Characteristic of REM High Yes High No No (can remember the dreams!) No
Nightmare disorder REM REM Anytime N/A N/A Yes High No No (can remember the dreams!) No
EEG = electroencephalogram, EMG = electromyogram

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