Night terror, also called sleep terror, is a sleep disorder causing feelings of panic or dread and typically occurring during the first hours of stage 3–4 non-rapid eye movement (NREM) sleep and lasting for 1 to 10 minutes. It can last longer, especially in children. Sleep terror is classified in the category of NREM-related parasomnias in the International Classification of Sleep Disorders. There are two other categories: REM-related parasomnias and other parasomnias. Parasomnias are qualified as undesirable physical events or experiences that occur during entry into sleep, during sleep, or during arousal from sleep.Sleep terrors usually begin in childhood and usually decrease as age increases. Factors that may lead to sleep terrors are young age, sleep deprivation, medications, stress, fever, and intrinsic sleep disorders. The frequency and severity differ among individuals; the interval between episodes can be as long as weeks and as short as minutes or hours. This has created a situation in which any type of nocturnal attack or nightmare may be confused with and reported as a night terror.Night terrors tend to happen during periods of arousal from delta sleep, or slow-wave sleep. Delta sleep occurs most often during the first half of a sleep cycle, which indicates that people with more delta-sleep activity are more prone to night terrors. However, they can also occur during daytime naps. Night terrors can often be mistaken for confusional arousal.While nightmares (bad dreams during REM sleep that cause feelings of horror or fear) are relatively common during childhood, night terrors occur less frequently.
In addition, nightmares appear ordinarily during REM sleep in contrast to night terrors, which occur in NREM sleep. Finally, individuals with nightmares can wake up completely and easily and have clear and detailed memories of their dreams.A distinction between night terrors and epileptic seizure is required. Indeed, an epileptic seizure could happen during the night but also during the day. To make the difference between both of them, an EEG can be done and if there are some anomalies on it, it would rather be an epileptic seizure. Assessment
The assessment of sleep terrors is similar to the assessment of other parasomnias and must include:
When the episode occurs during the sleep period
Age of onset
How often these episodes occur (frequency) and how long they last for (duration)
Description of the episode, including behavior, emotions, and thoughts during and after the event
How responsive the patient is to external stimuli during the episode
How conscious or aware the patient is, when awakened from an episode
If the episode is remembered afterwards
The triggers or precipitating factors
Sleep–wake pattern and sleep environment
Daytime sleepiness
Other sleep disorders that might be present
Family history for NREM parasomnias and other sleep disorders
Medical, psychiatric, and neurological history
Medication and substance use historyAdditionally, a home video might be helpful for a proper diagnosis. A polysomnography in the sleep laboratory is recommended for ruling out other disorders, however, sleep terrors occur less frequently in the sleep laboratory than at home and a polysomnography can therefore be unsuccessful at recording the sleep terror episode.