Parasomnias are disruptive sleep-related disorders that can occur during arousals from REM sleep or partial arousals from NREM sleep.


What are parasomnias?

Parasomnias are disruptive sleep-related disorders that can occur during arousals from REM sleep or partial arousals from NREM sleep. Parasomnias:

  • are characterized by undesirable physical or verbal behaviors, such as walking or talking during sleep;
  • occur in association with sleep, specific stages of sleep or sleep-wake transitions; and
  • can be divided into two groups—primary parasomnias and secondary parasomnias.

Primary parasomnias are disorders of sleep states, while secondary parasomnias are disorders of other organ systems that arise during sleep.

Primary parasomnias are marked by a simultaneous occurrence of elements of both wakefulness and sleep. Primary parasomnias are classified according to the stage of sleep in which they occur: rapid eye movement (REM) or non–rapid eye movement (NREM).

Secondary parasomnias are disorders of other organ systems that may take place during sleep. Secondary parasomnias may be quite common, but can be unrecognized, misdiagnosed, or ignored in clinical practice.

Types of Parasomnias


Nightmares are vivid nocturnal events that can cause feelings of fear, terror, and/or anxiety. Usually, the person having a nightmare is abruptly awakened from REM sleep and is able to describe detailed dream content. Usually, the person having a nightmare has difficulty returning to sleep. Nightmares can be caused by many factors including illness, anxiety, the loss of a loved one, or negative reactions to a medication. Call your doctor if nightmares occur more often than once a week or if nightmares prevent you from getting a good night's rest for a prolonged period of time.

Sleep Tip

Avoid alcohol close to bedtime. Although many people think Read More...

Sleep terrors/night terrors

A person experiencing a night terror or sleep terror abruptly awakes from sleep in a terrified state. The person may appear to be awake, but acts confused and is not able to communicate. Night terrors last about 15 minutes, after which time the person usually lies down and appears to fall back asleep. People who have sleep terrors usually don’t remember the events the next morning. Night terrors are similar to nightmares, but night terrors usually occur during Stages 3 and 4 sleep (deep sleep). People experiencing sleep terrors may pose dangers to themselves or others because of limb movements . Night terrors are fairly common in children aged three to five. This sleep disorder, which may run in families, also can occur in adults. Strong emotional tension and/or the use of alcohol can increase the incidence of night terrors among adults.

Sleepwalking (somnambulism)

Sleepwalking occurs when a person appears to be awake and moving around is actually asleep. Sleepwalkers have no memory of their actions. Sleepwalking most often occurs during deep non-REM sleep (stages 3 and 4 sleep) early in the night. It can occur during REM sleep in the early morning. This disorder is most commonly seen in children aged six to twelve; however, sleepwalking can occur among younger children, the elderly, and adults. Sleepwalking appears to run in families. Contrary to what many people believe, it is not dangerous to wake a person who is sleepwalking. The sleepwalker simply may be confused or disoriented for a short time upon awakening. Although waking a sleepwalker is not dangerous, sleepwalking itself can be dangerous because the sleepwalker is unaware of his or her surroundings and can bump into objects or can fall down.

Confusional arousals

Confusional arousals usually occur when a person is awakened from a deep sleep during the first part of the night. This disorder, which also is known as excessive sleep inertia or sleep drunkenness, involves an exaggerated slowness upon awakening. People experiencing confusional arousals react slowly to commands and may have trouble understanding questions that they are asked. In addition, people with confusional arousal often have problems with short-term memory.

Rhythmic movement disorders

This disorder, which often occurs just before a person falls asleep, occurs mostly in children who are one year old or younger. A child may lie flat, lift the head or upper body, then forcefully hit his or her head on the pillow. Rhythmic movement disorder, which also has been called "head banging," also can involve movements such as rocking on hands and knees.

Sleep talking

Sleep talking is a sleep-wake transition disorder. Although it usually is harmless, sleep talking can be disturbing to sleep partners or family members who witness it. Talk that occurs during sleep can be brief and involve simple sounds, or it can involve long speeches by the sleeper. A person who talks during sleep typically has no recollection of the actions. Sleep talking can be caused by external factors including fever, emotional stress or other sleep disorders.

Nocturnal leg cramps

Nocturnal leg cramps are sudden, involuntary contractions of the calf muscles during the night or periods of rest. The cramping sensation may last from a few seconds to 10 minutes, but the pain from the cramps may linger for a longer period. Nocturnal leg camps tend to be found in middle-aged or older populations, but people of any age can have nocturnal leg cramps. Nocturnal leg cramps differ from restless legs syndrome as the latter usually does not usually involve cramping or pain. The cause of nocturnal leg cramps is not known. Some cases of the disorder can occur without a triggering event, while other causes of leg cramps may be linked to prolonged sitting, dehydration, an overexertion of the muscles, or structural disorders (such as flat feet). Muscle-stretching, proper exercise, and adequate water intake may help prevent leg cramps.

Sleep paralysis

People with sleep paralysis are not able to move the body or limbs when falling asleep or waking up. Brief episodes of partial or complete skeletal muscle paralysis can occur during sleep paralysis. Sometimes sleep paralysis runs in families, but the cause of sleep paralysis is not known. This disorder is not harmful, but people experiencing sleep paralysis often are fearful because they do not know what is happening. An episode of sleep paralysis often is terminated by sound or touch. Within minutes, the person with sleep paralysis is able to move again.

Impaired sleep-related penile erections

This disorder occurs among men who are unable to sustain a penile erection during sleep that would be sufficiently rigid enough to engage in sexual intercourse. Men usually experience erections as a part of REM sleep, and impaired sleep-related erections may indicate physiological impotence.

Sleep-related painful erections

Erections are a normal component of REM sleep for men. In rare cases, however, erections become painful and cause a man to wake up. The treatment of sleep-related painful erections may involve drugs that suppress REM sleep (some anti-depressants, for example).

REM sleep cardiac arrhythmias

These arrhythmias take place during REM stage sleep. A cardiac arrhythmia is a change from the normal rate or control of the heart’s contractions. People who have coronary artery disease and whose blood oxygen is lowered by sleep-disordered breathing may be at risk for arrhythmias. Continuous Positive Airway Pressure (CPAP) treatment may reduce this risk.

REM sleep behavior disorder (RBD)

People with rapid eye movement (REM) sleep behavior disorder act out dramatic and/or violent dreams during REM sleep. REM sleep usually involves a state of sleep paralysis (atonia), but people with this condition move the body or limbs while dreaming. Usually, RBD occurs in men aged 60 and older, but the disorder also can occur in women and in younger people. In the diagnosis and treatment of RBD, potentially serious neurological disorders must be ruled out. Polysomnography (sleep tests) and drug treatments also can be involved in the diagnosis and treatment of this disorder.

Sleep bruxism

Sleep bruxism involves the involuntary, unconscious, excessive grinding or clenching of teeth during sleep. It may occur along with other sleep disorders. Sleep bruxism may lead to problems including abnormal wear of the teeth and jaw muscle discomfort. The severity of bruxism can range from mild cases to severe cases that involve evidence of dental injury. In some cases, bruxism can be prevented with the use of a mouth guard. The mouth guard, supplied by a dentist, can fit over the teeth to prevent teeth from grinding against each other.

Sleep enuresis

In this condition, also called bedwetting, the affected person is unable to maintain urinary control when asleep. There are two kinds of enuresis—primary and secondary. In primary enuresis, a person has been unable to have urinary control from infancy onward. In secondary enuresis, a person has a relapse after previously having been able to have urinary control. Enuresis can be caused by medical conditions (including diabetes, urinary tract infection, or sleep apnea) or by psychiatric disorders. Some treatments for bedwetting include behavior modification, alarm devices, and medications.

Nocturnal Paroxysmal Dystonia (NPD)

This disorder is sometimes marked by seizure-like episodes during non-REM sleep. The two kinds of NPD are short-acting and long-acting. Short-acting NPD is associated with seizures in 50% of cases. Short-acting NPD is thought to be a variation of frontal lobe epilepsy. Episodes of NPD typically recur several times per night.