Disorders of Arousal

Disorders of arousal, first described by Broughton (1990), have certain features in common during an episode: mental confusion and disorientation, automatic behaviors, relative nonreactivity to external stimuli, difficulty in being fully awakened, and fragmentary or absent dream recall. The next morning, the person has amnesia for the episode. Most characteristic of the disorders of arousal is their occurrence at a typical point in the sleep cycle, usually in the first third of the sleep period, at the point of transition from Stage 4 NREM sleep to REM sleep. Instead of the usual smooth transition to the lighter state of REM sleep, the person with a parasomnia arouses suddenly and manifests symptoms of autonomic discharge.

The onset of arousal disorders follows a developmental sequence. Sleep terrors appear in 2-year-olds. Attacks are usually frightening to parents, who may seek professional help. Typically, the attack begins 60-120 minutes after sleep onset, at the point in the sleep cycle when Stage 4 NREM sleep transitions to REM sleep. The child appears awake, with eyes open, and is screaming and seemingly frightened and agitated. Pounding heart, tachypnea, diaphoresis, and general disorientation reflect autonomic nervous system activation. In fact, the child is not awake, but is deeply asleep in Stage 4 NREM sleep. The child is difficult to soothe and is unaware of his or her surroundings.

He or she may fight with the person who is trying to console him or her. Although attacks are difficult to predict and patterns of occurrence are usually irregular, excessive fatigue or unusual stresses during the daytime have been noted to precipitate nighttime occurrences. Because sleep terror is not likely to occur when studied in a sleep laboratory, it may be more relevant to ask parents to use a camcorder to record episodes at home.

Sleepwalking begins in slightly older children of preschool and school age. Like sleep terrors, sleepwalking is associated with autonomic activation at the point of transition in the sleep cycle from Stage 4 NREM sleep to REM sleep, typically 60-120 minutes after sleep onset. Instead of screaming, the child sits upright in bed or walks. Behaviors are automatic and purposeless, and body movements are poorly coordinated. The sleepwalking child is difficult to arouse and, when awakened, is confused and disoriented. Sleepwalking is dangerous, because the child may injure him- or herself by falling or crashing into objects. In contrast, children and adolescents who present with "sleep" behaviors characterized by complex, purposeful actions, such as leaving the home at night to rendezvous with friends or preparing nighttime snacks, are generally not exhibiting disorders of arousal. More psychological explanations, including malingering, conduct disorder, and dissociative states, need to be considered.

Unless the parasomnia is intractable in terms of frequency and persistence, special intervention is not needed. Reassurance and explanation often provide sufficient support for the child and family. Parents should try to guide the sleepwalking child back to bed or provide comfort to the child in the midst of a sleep terror attack. Awakening the child from either is difficult and does not shorten the attack. It is important to safe-proof the environment for children who walk in their sleep. Setting alarms that trigger when the child rises from bed, sealing windows, and locking doors may be necessary to avoid the child's injuring himself or herself.