Night terror

A night terror, sleep terror or pavor nocturnus is a parasomnia disorder, causing feelings of terror or dread, and typically occurring in the first few hours of sleep during stage 3 or 4 non-rapid eye movement (NREM) sleep.^[1] Night terrors tend to happen during periods of arousal from delta sleep, also known as slow wave sleep.^[2][3][4] During the first half of a sleep cycle, delta sleep occurs most often, which indicates that people with more delta sleep activity are more prone to night terrors.^[3] However, they can also occur during daytime naps.^[5]

Night terrors have been known since the ancient times, although it was impossible to differentiate them from nightmares until rapid eye movement was discovered.^[4] While nightmares (bad dreams that cause feelings of horror or fear) are relatively common during childhood, night terrors occur less frequently according to the American Academy of Child and Adolescent Psychiatry.^[6] The prevalence of sleep terror episodes has been estimated at 1%-6% among children and at less than 1% of adults.^[7] Night terrors can often be mistaken for the disorder of confusional arousal.^[2] Sleep terrors begin between ages 3 and 12 years and then usually dissipate during adolescence. In adults, they most commonly occur between the ages of 20 to 30. Though the frequency and severity vary between individuals, the episodes can occur in intervals of days or weeks, but can also occur over consecutive nights or multiple times in one night.^[3][5]

Night terrors are largely unknown to most people, creating the notion that any type of nocturnal attack or nightmare can be confused with and reported as a night terror.^[4]

Associated features

The universal feature of night terrors is inconsolability.^[8] During night terror bouts, patients are usually described as 'bolting upright' with their eyes wide open and a look of fear and panic on their face. They will often scream. Further, they will usually sweat, exhibit rapid respiration, and have a rapid heart rate (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 individual is trying to protect themselves and/or escape from a possible threat which can lead to physical injury of the individual.^[5] Although children may seem to be awake during a night terror, they will appear confused, be 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 awoken, they will lash out at the person which can be dangerous for that individual.^[3] Most people who experience this disorder are amnesic, or partially amnesic from the incident the next day.^[2] Sleepwalking is another predisposition for the disorder.^[4][9] Sleepwalking and night terrors are different manifestations of the same parasomnia disorder.^[4]

During lab tests, subjects are known to have very high voltages of electroencephalography (EEG) delta activity, an increase in muscle tone, and a doubled increase in heart rate, if not more. Brain activities during a typical episode show theta and alpha activity when using an EEG. It is also common to see abrupt arousal from NREM sleep that does not progress into a full episode of a night terror. These episodes can include tachycardia. Night terrors are also associated with intense autonomic discharge of tachypnea, flushing, diaphoresis, and mydriasis.^[8]

In children with night terrors, there is no increased occurrence of psychiatric diagnoses.^[10] However, in adults who suffer from sleep terror disorder there is a close association with psychopathology or mental disorders. There may be an increased occurrence of sleep terror disorder particularly with those that have suffered from post-traumatic stress disorder or PTSD and generalized anxiety disorder. It is also likely that some personality disorders may occur in individuals with sleep terror disorder, such as dependent, schizoid, and borderline personality disorders.^[10] There have been some symptoms of depression and anxiety that have increased in individuals that have suffered from frequent night terrors. Low blood sugar is associated with both pediatric and adult night terrors.^[5][11] A study of adults with thalamic lesions of the brain and brainstem have been occasionally associated with night terrors.^[12] Night terrors are closely linked to sleepwalking and frontal lobe epilepsy.^[13]

Susceptibility and variation

There is some evidence that a predisposition to night terrors and other parasomnia disorders can be congenital. Individuals frequently report that past family members have had either episodes of sleep terrors or sleepwalking. In some studies, a ten-fold increase in the prevalence of the disorder in first-degree biological relatives has been observed—however, the exact link to inheritance is not known.^[5] Familial aggregation has been found suggesting that there is an autosomal mode of inheritance.^[14] In addition, some laboratory findings suggest that sleep deprivation and having a fever can increase the likelihood of a night terror episode occurring.^[7] Other contributing factors include nocturnal asthma, gastroesophageal reflux, and central nervous system medications.^[14] Special consideration must be used when the subject suffers from narcolepsy, as there may be a link between the disorders. There have been no findings that show a cultural difference between manifestations of sleep terror disorder, though it is thought that the significance and cause of sleep terrors differ within cultures.

Also, older children and adults provide highly detailed and descriptive images associated with their sleep terrors than younger children, who either cannot recall or only vaguely remember. Sleep terrors in children are also more likely to occur in males than females; in adults, the ratio between sexes are the same.^[5] A longitudinal study of twins, both monozygotic and dizygotic were examined and found to show that a high concordance rate of night terror was found much more in monozygotic twins than in dizygotic.^[14][15]

Though the symptoms of night terrors in adolescents and adults are similar, the etiology, prognosis, and treatment are qualitatively different. There is some evidence that suggests that night terrors can occur if the sufferer does not eat a proper diet, does not get the appropriate amount or quality of sleep (e.g. sleep apnea), or is enduring stressful events. Adult night terrors are much less common, and often respond best to treatments that rectify causes of poor quality or quantity of sleep.

DSM-IV-TR diagnosis

The DSM-IV-TR diagnostic criteria for sleep terror disorder requires:^[7]

• recurrent periods where the individual abruptly wakes from sleeping with a scream
• the individual experiences intense fear and symptoms of autonomic arousal such as increased heart rate, heavy breathing, and increased perspiration
• the individual cannot be soothed or comforted during the episode
• the individual is unable to remember details of the dream or details of the episode
• the occurrence of the sleep terror episode causes clinically significant distress or impairment in the individual's functioning
• the disturbance is not due to the effects of a substance or general medical condition

Adults

Night terrors in adults have been reported in all age ranges.^[16] Though the symptoms of night terrors in adolescents and adults are similar, the etiology, prognosis and treatment are qualitatively different. These night terrors can occur each night if the sufferer does not eat a proper diet, get the appropriate amount or quality of sleep (e.g. sleep apnea), is enduring stressful events, or if he or she remains untreated. Adult night terrors are much less common, and often respond to treatments to rectify causes of poor quality or quantity of sleep. Night terrors are classified as a Mental and behavioral disorder in the ICD ^[17] A study done about night terrors in adults showed that other psychiatric symptoms were prevalent in most patients experiencing night terrors hinting at the comorbidity of the two.^[14] There is some evidence of a link between adult night terrors and hypoglycemia.^{[18][citation needed]}

When a night terror happens, it is typical for a person to wake up screaming and kicking and to be able to recognize what she or he is saying. The person may even run out of the house (more common among adults) which can then lead to violent actions.^[19] It has been found that some adults who have been on a long-term intrathecal clonidine therapy show side effects of night terrors, such as feelings of terror early in the sleep cycle.^[20] This is due to the possible alteration of cervical/brain clonidine concentration.^[16] In adults, night terrors can be symptomatic of neurological disease and can further investigate through an MRI procedure.^[21]

Children

The sleep disorder of night terrors typically occurs in children between the ages of three to twelve years, with a peak onset in children aged three and a half years old.^[22] An estimated one to six percent of children experience night terrors. Boys and girls of all backgrounds are affected equally. The disorder usually resolves during adolescence.^[22] Sleep disruption is parents’ most frequent concern during the first years of a child’s life. Half of all children develop a disrupted sleep pattern serious enough to warrant assistance of a physician.^{[citation needed]} In children younger than three and a half years old, peak frequency of night terrors is at least one episode per week. Among older children, peak frequency of night terrors is one or two episodes per month. Children experiencing night terrors may be helped by a pediatric evaluation. During such evaluation, the pediatrician may also be able to exclude other possible disorders that might cause night terrors.^[22]

Treatment

It may be helpful to reassure the person that he or she will outgrow this disorder. There is some indication that night terrors can result from being overtired, in which case interventions such as creating a bedtime schedule can increase the chances of restful sleep. If the night terrors are more chronic, however, some evidence suggests that the sufferer should be awakened from sleep just before the time when the terrors typically occur to interrupt the sleep cycle. In some cases, a child who has night terrors will require additional comfort and reassurance during the day and before bedtime. Psychotherapy or counseling can be helpful in many cases. Benzodiazepine medications (such as diazepam) used at bedtime will often reduce the occurrence of night terrors; however, medication is rarely recommended to treat this disorder.^[23]

Prevalence of night terrors is unknown or unclear because there have been very few epidemiological studies over time.^[14][24][25]

See also

• Ephialtes (illness)
• Nightmare
• Sleep paralysis
• Horror and terror

References

External links

• Night Terror Resource Center
• National Institutes of Health, Medline Plus: Night Terrors
• National Library of Medicine - Medical Subject Headings: Night Terrors