Parasomnias are unusual behaviors that occur during sleep.

Various unconscious and largely unremembered behaviors can occur during sleep in children and adults. Just before falling asleep, almost all people occasionally experience brief, involuntary jerks of the arms or the entire body. Occasionally, the legs jerk. Some people also experience sleep paralysis (attempting but being unable to move) or brief fleeting images or thoughts when they are just falling asleep or awakening. People may clench or grind their teeth or have nightmares. Sleepwalking, head-banging, and night terrors are more common among children and can be very distressing for their parents. Usually, children do not remember these episodes.

Night terrors are frightening episodes which result in sitting up, screaming, and flailing about. The eyes are wide open, and the heart races. Episodes usually occur during nonrapid eye movement (non-REM) stages of sleep, typically in the first few hours of the night. Night terrors are more common among children. Children should not be awakened because doing so makes them even more frightened. Although children appear that they are highly distressed, they have no memory for the events or mental images after awakening and do not suffer psychologic problems as a result of these behaviors. Parents need not be overly distressed. Children usually stop having episodes when they become older. Episodes in adults are often associated with psychologic problems. Treatment with certain benzodiazepines, such as clonazepam, or tricyclic antidepressants, such as imipramine, may help. Adults may benefit from psychotherapy or drug treatment.

Nightmares are vivid, frightening dreams, followed by sudden awakening. Children and adults may have nightmares. Nightmares occur during rapid eye movement (REM) sleep. They are more likely to occur when people are under stress, have a fever, are excessively tired, or have consumed alcohol. Treatment, if necessary, focuses on the underlying problem.

Sleepwalking (somnambulism),most common in late childhood and adolescence, is walking in a semiconscious manner without being consciously aware of it. It occurs during the deepest stages of sleep. People do not dream while sleepwalking—in fact, brain activity during sleepwalking, although abnormal, is more like that of a wakeful state than of a sleeping one. Sleepwalkers may mumble repetitiously and can hurt themselves by walking into obstacles. Most sleepwalkers have no memory of sleepwalking.

No specific treatment is available, but the sleepwalker can be gently led back to bed. Leaving a light on in the bedroom or adjacent hall sometimes reduces the tendency to sleepwalk. Forcibly awakening the sleepwalker may provoke an agitated reaction and is not advised. Obstacles or breakable objects in the sleepwalker's potential path should be removed, and windows should be kept closed and locked. Benzodiazepines, particularly diazepam and clonazepam may help.

Rapid eye movement behavior disorder involves speaking (often profanely) and sometimes making violent movements during REM sleep, usually in response to a dream. Unlike night terrors, people with rapid eye movement behavior disorder are sometimes aware of having dreamed vividly during these episodes when they wake up the next day. Violent movements may include waving the arms, punching, and kicking. The violent behavior is not intentional and is not directed at anyone. The disorder is more common among the elderly, particularly those who have disorders that cause degeneration of the brain (such as Parkinson's disease or Alzheimer's disease). People may inadvertently injure themselves or their bed partner. Also, this behavior interferes with sleep, making people tired and sleepy during the day. Doctors can often diagnose this disorder based on symptoms reported by the person or the person's bed partner. But if they cannot, polysomnography with electromyography (EMG) is usually done.

There is no cure for the disorder. But clonazepam, a benzodiazepine (which is a sedative), relieves symptoms in most people. A low dose is effective. The drug is usually continued indefinitely. Bed partners should be warned about the possibility of harm and may wish to sleep in another bed until the drug begins to work. People with the disorder should remove sharp objects and furniture from next to their bed.

Last full review/revision March 2008 by Karl Doghramji, MD