< Back

Sleep Related Behaviors (Parasomnias)

Parasomnias are disruptive behaviors in sleep that occur during an arousal from rapid eye movement (REM) sleep or non rapid eye movement (NREM) sleep.  Parasomnias can be primary or secondary to another underlying sleep or medical disorder.  While parasomnias can occur at any age, certain types such as night terrors and sleepwalking are more common in younger people while other types like REM Behavior Disorder are more common in older individuals.  The most common types of parasomnias are:


Sleepwalking consists of a series of complex behaviors that are usually initiated during arousals from slow-wave sleep and culminate in walking around with an altered state of consciousness and impaired judgment.  Episodes usually occur in the first third or half of the night when the largest amount of slow wave sleep is usually present.  Episodes may increase during times of increased slow wave sleep such as when recovering from sleep deprivation.


Episodes often begin with sitting up in bed and looking about in a confused manner before walking; episodes can also begin with immediately leaving the bed and walking or even “bolting” from the bed and running. Frantic attempts to escape an imminent perceived or dreamed threat can occur. Agitated, belligerent, or violent behavior can also occur. The person may be difficult to awaken but, when awakened, is often confused. There is usually amnesia for these episodes, although adults can remember fragments of episodes and sometimes will have considerable recall for the events. The ambulation may terminate spontaneously, at times in inappropriate places, or the sleepwalker may return to bed, lie down, and continue to sleep without reaching alertness at any point.  Sleep-talking and shouting can accompany these events.

Evaluation of sleepwalking involves an overnight sleep study to determine any underlying causes such as sleep apnea.  Treatment involves first treating any underlying disorders that could be increasing arousals such as sleep apnea.  Low dosages of certain medications can also be used.  Most importantly, safeguarding the environment to prevent injury during episodes is a must.

Sleep Terrors

Sleep terrors consist of arousals from slow-wave sleep accompanied by such behaviors as crying, intense fear, shortness of breath, rapid heart beat, sweating, flushing, increased muscle tone, and dilated pupils.  The person usually sits up in bed; is unresponsive to external stimuli; and, if awakened, is confused and disoriented. However, bolting out of bed and running is not uncommon in adults and can also be associated with violent behaviors. Generally, there is no memory for the event.  Sometimes there is prolonged inconsolability with a sleep terror in children or adults.

Sleep terrors usually occur in the first third of the night and are more common in children.  However, episodes do occur at any age.  Sleep deprivation, fatigue, irregular routine, or emotional stress during the day can trigger episodes.

Sleep terrors may improve with age.  It is important to obtain adequate amounts of sleep and address daytime stressors to minimize sleep terrors.

Confusional Arousals

Confusional arousals consist of mental confusion or confusional behavior during or following arousals from sleep, typically from slow-wave sleep in the first part of the night, but also upon attempted awakening from sleep in the morning.

The individual is disoriented in time and space, with slow speech, foggy thinking, poor memory, and blunted response to questions or requests. During confusional arousals, especially during forced awakenings, behavior may be very inappropriate, and episodes can last minutes to several hours. The individual may appear to be awake during some or most of a confusional arousal.

Confusional arousals may be related to underlying disorders that increase arousals from sleep such as sleep apnea, restless legs syndrome, or nocturnal asthma.  Other problems such as migraines, fever, travel, irregular sleep-wake schedules, and abrupt sleep loss can trigger episodes.  Treatment of the underlying condition as well as safety precautions are important.

REM Behavior Disorder

REM sleep behavior disorder (RBD) is characterized by abnormal behaviors emerging during REM sleep that cause injury or sleep disruption. Dream enactment behaviors sometimes associated with injury to the person or bed partner are common.  RBD is also associated with certain features on a sleep study including increased muscle tone during REM sleep.

A complaint of sleep related injury is common with RBD, which usually manifests as an attempted enactment of distinctly altered, unpleasant, action-filled, and violent dreams in which the individual is being confronted, attacked, or chased by unfamiliar people or animals. Typically, at the end of an episode, the individual awakens quickly; becomes rapidly alert; and reports a dream with a coherent story, with the dream action corresponding to the observed sleep behaviors.

Medical attention is usually sought after sleep related injury has occurred to either the person or the bed partner and rarely because of sleep disruption. Because RBD occurs during REM sleep, it usually appears at least 90 minutes after sleep onset.  Vigorous or violent episodes typically occur about once weekly but may occur as often as four times nightly for several consecutive nights or considerably longer.

RBD is usually a longstanding and progressive disorder, and it is more common in older individuals. It is associated with certain neurologic conditions such as Parkinson’s disease.  There is an acute form of RBD that emerges during intense REM sleep rebound states, such as during withdrawal from alcohol and sedative-hypnotic agents, with certain medication use, or with drug intoxication.

Safety precautions to the patient and bed partner are key in treatment of RBD.   Medication may be helpful as well as treatment of any underlying sleep disorder.

Sleep Paralysis

Sleep paralysis is characterized by an inability to perform voluntary movements at sleep onset (hypnagogic or predormital form) or on waking from sleep (hypnopompic or postdormital form) in the absence of a diagnosis of narcolepsy. The event is characterized by an inability to speak or to move the limbs, trunk, and head. Breathing and consciousness are unaffected, and the person has full awareness during the episode.  An episode of sleep paralysis lasts seconds to minutes. It usually resolves spontaneously but can be aborted by sensory stimulation, such as being touched or spoken to, or by the patient making intense efforts to move. The frequency of episodes varies from once in a lifetime to several times a year.

Sleep paralysis is a common phenomenon and occurs in otherwise normal sleepers.  It has been associated with increased stress, excessive alcohol consumption, sleep deprivation, and narcolepsy.  Treatment involves avoiding triggers such as sleep deprivation and alcohol.  If sleep paralysis is frequent, evaluation for narcolepsy may be necessary.


Nightmare disorder is characterized by recurrent nightmares, which are disturbing mental experiences that generally occur during REM sleep and that often result in awakening.

Nightmares are coherent dream sequences that seem real and become increasingly more disturbing as they unfold. Emotions usually involve anxiety, fear, or terror but frequently also anger, rage, embarrassment, disgust, and other negative feelings. Ability to detail the nightmare’s contents upon awakening is common in nightmare disorder. Because nightmares typically arise during REM sleep, they may occur at any moment that REM propensity is high, usually in the last half of the night.

Nightmares may be related to both psychological and physical causes.  Anxiety disorders, post-traumatic stress disorder, illness, or even uncomfortable sleeping conditions can increase nightmares.  Treatment involves treating the underlying condition and reducing stress levels.  Yoga, regular exercise, and stress relief may be helpful.