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.
Recurrent episodes of incomplete awakening from sleep, usually occurring during the first third of the major sleep episode, accompanied by the following:
No or little (e.g., only a single visual scene) dream imagery is recalled.
Amnesia for the episodes is present.
The episodes cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
The disturbance is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication).
Co-existing mental and medical disorders do not explain the episodes of sleep terrors.
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.
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) | 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 |
REM
ember events (i.e. - no confusion, no amnesia) in REM 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 |