Arousal disorders are characterized by confusion and automatic behavior after sudden arousal from delta sleep. The tendency to arouse from delta sleep spontaneously is a familial trait unrelated to epilepsy. Most patients have an affected first-degree relative; the cooccurrence of these disorders in the same patient is common. Onset in childhood and resolution by adolescence are typical, but episodes may recur or occur for the first time with greater severity in adolescence and adulthood. Stress, sleep deprivation, and any factors that may contribute to sleep disruption are clear exacerbants. Sleep-disordered breathing and nocturnal alcohol consumption are common precipitants of arousal in the predisposed adult population. Psychopathologic abnormality - especially anxiety, depression, obsessive compulsive behavior, and phobia - is said to be more common in the symptomatic adult.
“Confusional arousals consist of confusion during and following arousals from sleep, most typically from deep sleep in the first part of the night.” These episodes are most commonly seen in forced arousals from delta sleep, particularly in individuals with a family or personal history of sleepwalking or sleeptalking, and in children younger than the age of 5. Amnesia for the events during the arousal is typical. This is predominantly a problem for individuals, such as physicians, who are called at night and must react appropriately.
“Sleepwalking consists of a series of complex behaviors that are initiated during slow wave sleep and result in walking during sleep.” Sleepwalkers characteristically arouse during the first third of the night from delta sleep, leave the bed in a confused state, and perform complex, automatic acts. Some episodes of sleepwalking are initiated by sleep terror (discussed later), in which case the behavior exhibited may be violent, as the subject tries to combat a perceived threat. More routine behavior, such as eating and urinating, may be performed in a remarkably stereotyped fashion idiosyncratic to the subject. The patient may awaken during the behavior feeling embarrassed and bewildered. Most often the patient returns to bed and has no memory of the episode. Patients with this disorder are at risk of injuring themselves and their bed partners. Care must be taken to secure the sleep environment to prevent falling from heights. Occasionally, dangerous objects such as knives and guns need to be made inaccessible. Although sleepwalking is frequently perceived as amusing, it may entail social stigma, especially when there is associated violence. Murders have been committed during apparent sleepwalking, and serious personal injury occurs frequently.
“Sleep terrors are characterized by a sudden arousal from slow wave sleep with a piercing scream or cry, accompanied by automatic and behavioral manifestations of intense fear.” Typically, the individual arouses within the first 2 hours of sleep, sits bolt upright, and screams. Marked tachycardia, mydriasis, and sweating may be evident. The subject is agitated, confused, and difficult to console or arouse fully. There is no detailed dream recall, but a single terrifying image, such as a demon, insect, or intruder, may be reported. Generally sleep is resumed in a few minutes, with amnesia for the entire episode the next morning.
In patients with arousals from delta sleep, polysomnography may show characteristic high-voltage synchronous delta activity followed by arousal, even in the absence of a clinical episode. Most patients can recognize factors that tend to exacerbate their sleep terrors or sleepwalking. If episodes persist after attempts to control the underlying precipitants, a small nightly dose of clonazepam is usually effective.
Revision date: June 21, 2011
Last revised: by Jorge P. Ribeiro, MD