Sleep Terrors

Sleep Terrors (also known as Night Terrors) are a non-rapid eye movement sleep disorder characterized by the repeated occurrence of precipitous awakenings from sleep, usually beginning with a panicky scream or cry. Sleep terrors usually begin during the first third of the major sleep episode and last 1-10 minutes, but they may last considerably longer, particularly in children. The episodes are accompanied by impressive autonomic arousal and behavioral manifestations of intense fear.

  • The prevalence of sleep terrors in the general population is unknown.
  • The prevalence of sleep terror episodes (as opposed to sleep terror disorder) is approximately 36.9% at 18 months of age, 19.7% at 30 months of age, and 2.2% in adults.[1]
  • Sleep terrors usually begin in children between ages 4 to 12, and will spontaneously resolve by adolescence[2]
  • Those with adult-onset sleep terrors usually develop it between ages 20 to 30, and there is often a chronic course that waxes and wanes
  • The episodes usually occur between intervals of days to weeks, but can occur nightly for some
Risk Factors
Criterion A

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

  1. 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.
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 sleep terrors.

Individuals do not remember the sleep terrors!

As per criterion C, individuals experiencing night terrors do not remember the event! This can be a helpful differentiation point with other diagnoses like nocturnal panic attacks.

During an episode, the individual is difficult to awaken or comfort. If the individual awakens after the sleep terror, little or none of the dream, or only fragmentary, single images, are recalled. During a typical episode of sleep terrors, the individual abruptly sits up in bed screaming or crying, with a frightened expression and autonomic signs of intense anxiety (e.g., tachycardia, rapid breathing, sweating, dilation of the pupils). The individual may be inconsolable and is usually unresponsive to the efforts of others to awaken or comfort him or her. Sleep terrors are also called “night terrors” or “pavor nocturnus.”

During a typical episode of sleep terrors, there is often a sense of overwhelming dread, with a compulsion to escape. Although fragmentary vivid dream images may occur, a story-like dream sequence (as in nightmares) is not reported. Most commonly, the individual does not awaken fully, but returns to sleep and has amnesia for the episode on awakening the next morning. Usually only one episode will occur on any one night. Occasionally several episodes may occur at intervals throughout the night. These events rarely arise during daytime naps.

Sedative use, sleep deprivation, sleep-wake schedule disruptions, fatigue, and physical or emotional stress increase the likelihood of episodes. Fever and sleep deprivation can produce an increased frequency of NREM sleep arousal disorders. A family history for sleepwalking or sleep terrors may occur in up to 80% of individuals who sleepwalk. The risk for sleepwalking is further increased (to as much as 60% of offspring) when both parents have a history of the disorder.

Individuals with sleep terrors frequently have a positive family history of either sleep terrors or sleepwalking, with as high as a 10-fold increase in the prevalence of the disorder among first-degree biological relatives. Sleep terrors are much more common in monozygotic twins as compared with dizygotic twins. The exact mode of inheritance is unknown.

  • NREM sleep disorders can occur during any stage NREM sleep but are most common during deep NREM sleep (slow-wave sleep or delta-wave sleep).
    • They are most likely to appear in the first third of the night and do not commonly occur during daytime naps.
  • During the episode, the polysomnogram may be obscured with movement artifact. In the absence of such artifact, the electroencephalogram (EEG) typically shows theta or alpha frequency activity during the episode, indicating partial or incomplete arousal.
  • Unlike arousals from REM sleep associated with nightmares, in which there is an increase in heart rate and respiration prior to the arousal, the NREM sleep arousals of sleep terrors begin suddenly from sleep, without anticipatory autonomic changes.
    • Symptoms include doubling or tripling of the heart rate. The pathophysiology is poorly understood, but there appears to be instability in the deeper stages of NREM sleep.
  • Reassurance and education is important, and ensuring a safe sleeping environment
  • Avoid sleep deprivation and ensure a consistent sleep cycle
  • Avoid the use of alcohol and any offending drugs that may cause parasomnias
  • Safety planning: padding on furniture or floor near bed, barriers at top of stairs, securing doors and windows with locks, removing sharp objects, locks on refrigerators.
  • Clonazepam 0.25mg qHS may be used.[3]
  • SSRIs and TCAs may also be used in the treatment of NREM parasomnias
  • Medical: febrile illness, alcohol, sleep deprivation, stress
  • Rule out brain insults, brain gliomas, epilepsy, cardiac insufficiency
  • Medication-induced complex behaviours: hypnotics, neuroleptics, stimulants, anti-histamines and anti-arrhythmics
  • 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
  • Night eating syndrome

There are key differences in the diagnostic criteria between nightmares and sleep terrors (night terrors), and the table below outlines these differences. It is important to remember that night terrors occur during deep non-REM sleep (EEG shows a slow wave sleep pattern). Night terrors are technically not dreams, but more of a sudden reaction of fear that occurs during the transition from one sleep stage to another.

Sleep Terrors (Night Terrors) vs. Nightmares

Adapted from Barton Schmitt, MD (2007)
Sleep Terrors (Night Terrors) Nightmares
Peak age 1-4 years 3-12 years
Prevalence 2% of children 100% of children
Sleep time First 2 hours Last 4 hours
Stage of sleep Stage 3/4 (slow wave sleep) REM-related
Movement Active Little
Autonomic changes Extreme Mild
Recognizes parent No Yes
Can awaken No Yes
Consolable No Yes
Dreams remembered No Yes
Confusion/disorientation Yes No
History of sleep walking Yes No
Difficult to console Yes No
Potential to hurt self/others Yes No


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
1) American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Arlington, VA.
2) American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Arlington, VA.