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. As a result, 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. The prevalence of sleep terrors in general is unknown. The number of small children who experience sleep terror episodes (distinct from sleep terror disorder, which is recurrent and causes distress or impairment) is estimated at 36.9% at 18 months of age and at 19.7% at 30 months. In adults, the prevalence is lower, at only 2.2%. Night terrors have been known since ancient times, although it was impossible to differentiate them from nightmares until rapid eye movement was studied.
Signs and symptoms
The universal feature of night terrors is inconsolability—very similar to that of a panic attack. During night terror bouts, sufferers are usually described as "bolting upright" with their eyes wide open and a having look of fear on their face. Individuals with night terrors will often yell, scream, or attempt to speak, but such speech is frequently incomprehensible. Furthermore, they usually sweat, exhibit rapid breathing, and have a rapid heart rate (i.e., autonomic signs). In some cases, individuals are likely to have even more elaborate motor activity, such as a thrashing of limbs—which may include punching, swinging, or fleeing motions. There is a sense that the individuals are trying to protect themselves and/or escape from a possible threat of bodily injury. Although sufferers may seem awake during a night terror, they will appear confused, inconsolable, and/or unresponsive to attempts to communicate with them and may not recognize others familiar to them. Occasionally, when a person with a night terror is awakened, they will lash out at the one awakening them, which can be dangerous to that individual. Most individuals who experience terrors do not remember the incident the next day, although brief dream images or hallucinations may occur and be recalled. Sleepwalking is also common during night terror bouts, as sleepwalking and night terrors manifest the same parasomnia. Both children and adults may display behaviour indicative of attempting to escape a terrifying event; some may thrash about or get out of bed and begin walking or running around aimlessly while inconsolable, increasing the risk of accidental injury. The risk of injury to others may be exacerbated by inadvertent provocation by nearby people, whose efforts to calm the individual may result in a physically violent response from the individual as they attempt to escape. During polysomnography, individuals with night terrors are known to have very high voltages of electroencephalography (EEG) delta activity, an increase in muscle tone, and a doubled or faster heart rate. Brain activities during a typical episode show theta and alpha activity when monitored with an EEG. Episodes can include tachycardia. Night terrors are also associated with intense involuntary rapid and shallow breathing, profuse sweating, reddening of the skin, and pupil dilation. Abrupt but calmer arousal from non-rapid eye movement sleep, short of a full night terror episode, is also common. In children with night terrors, there is no increased occurrence of psychiatric diagnoses. However, in adults with night terrors, there is a close association with psychopathology and mental disorders. There may be an increased occurrence of night terrors—particularly among those with post-traumatic stress disorder (PTSD) and generalized anxiety disorder (GAD) and anti-depressants used to treat these disorders. It is also likely that some personality disorders may occur in individuals with night terrors, such as dependent, schizoid, and borderline personality disorders. There have been some symptoms of depression and anxiety that have increased in individuals that have frequent night terrors. Low blood sugar is associated with both pediatric and adult night terrors. A study of adults with thalamic lesions of the brain and brainstem have been occasionally associated with night terrors. Night terrors are closely linked to sleepwalking and frontal lobe epilepsy.
Children Night terrors typically occur in children between the ages of three and twelve years, with a peak onset in children aged three and a half years old. An estimated 1–6% of children experience night terrors. Children of both sexes and all ethnic backgrounds are all affected. In children younger than three and a half years old, the peak frequency of night terrors is at least one episode per week (up to 3–4 in rare cases). Among older children, the peak frequency of night terrors is one or two episodes per month. The children will most likely not recollect the episode the next day. Pediatric evaluation may be sought to exclude the possibility that seizure disorders or breathing problems cause night terrors. Most children will outgrow sleep terrors.
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