Parasomnias are disruptive sleep-related disorders that can occur during arousals from REM sleep or partial arousals from Non-REM sleep.
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 sleep for a prolonged period of time.
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 is confused and unable 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 dont remember the events the next morning. Night terrors are similar to nightmares, but night terrors usually occur during 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 occurs when a person appears to be awake and moving around but 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 fall down.
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
Rhythmic movement disorder occurs mostly in children who are one year old or younger. A child may lie flat, lift the head or upper body, and 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. The disorder usually occurs just before a person falls asleep.
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 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, exercise, and adequate water intake may help prevent leg cramps.
People with sleep paralysis are not able to move their 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 antidepressants, for example).
REM sleep cardiac arrhythmias
A cardiac arrhythmia is a change from the normal rate or control of the hearts contractions. People who have coronary artery disease and whose blood oxygen is lowered by sleep-disordered breathing may be at risk for arrhythmias, which take place during REM sleep. 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 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 (bedwetting)
In this condition, 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. Most evidence points to NPD being a form of epilepsy. Episodes of NPD typically recur several times per night.
Reviewed by The Sleep Medicine Center at The Cleveland Clinic.
Edited by Michael J. Breus, PhD, WebMD, September 2004.
Portions of this page © The Cleveland Clinic 2000-2005
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Last Editorial Review: 6/20/2005