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What are parasomnias? They are undesirable events that occur during sleep. They do not in and of themselves cause insomnia or excessive sleepiness. They can be movements, speech, or experiences.


Parasomnias can be thought of as gray areas between the different states of wakefulness, non-REM (NREM) sleep, and REM sleep. Therefore, parasomnias are divided up under these headings, with an additional grouping of parasomnias that doesn't fall clearly into any of these and is characterized under the heading "other."

Parasomnias linked with RNEM sleep

These are classified as incomplete arousals from NREM sleep. There are 3 types of NREM arousal parasomnias: 1) Confusional arousals, 2) Sleep terrors, and 3) Sleepwalking. All of these parasomnias are more likely to occur if anything deepens or disrupts sleep, such as previous sleep deprivation.


Confusional Arousals: Also known as sleep drunkenness, this arousal disorder is generally seen in the first third of the night. The person is disoriented in time and space and performs inappropriate behaviors, such as getting dressed for work several hours too early. These events are usually brought on by forced awakenings from slow-wave sleep, such as when a dog barks or a phone rings. The person usually has little or no memory of the event.


Sleepwalking: Also known by the technical term "somnambulism," this arousal disorder is commonly seen in young children. It is less frequent in adults. Sleepwalking includes a range of movement from simply sitting up in bed to making frantic attempts to escape. During the event, the person is difficult to awaken, and doing so can lead to violence. Both suicides and homicides have been reported. This disorder of sleep is seen in the first third of the night and originates from slow-wave sleep. It occurs more frequently if the person has been sleep-deprived. The person does not remember the event.


Sleep terrors: Also known as "night terrors," this dramatic arousal disorder involves a sudden arousal from slow-wave sleep that is accompanied by a loud scream or shriek. The behavior that accompanies the screaming is usually seen in persons experiencing intense fear. The person displays rapid heartbeat and breathing, flushed skin, and perspiration. Initial attempts to awaken the person are usually not successful and there is no dream imagery or memory associated with it.

Is this you?

Sleep-wake transition disorders occur in the transitions from wake to sleep, from sleep to wake, and rarely, from one sleep stage to another. These all occur in people who are otherwise healthy. They all can occur with such severity or frequency that they can cause discomfort, embarrassment, anxiety, and/or disturb the bed partner's sleep.


Rhythmic Movement Disorder: This is seen almost exclusively in infants or toddlers and involves banging the head or rolling the body rhythmically as the person moves from drowsiness to sleep. It usually resolves by the age of 2-3 years and is seen predominantly in males at a ratio of 4:1.


Sleep Starts: Also known as "hypnic jerks," these have been experienced by most people. It involves a brief jerk of the legs, or occasionally the head or arm, as a person falls asleep. They are frequently related to a feeling of falling. They are essentially benign, although if they occur repeatedly they can cause sleep-onset insomnia. Caffeine, stimulants, stress, or intense physical work may make them worse. A sleep study will help differentiate between sleep starts and other sleep disorders such as Periodic Limb Movements (PLMs), Obstructive Sleep Apnea (OSA) or seizures.


Sleep Talking: Also known by the term "somniloquy," sleep talking is described as sounds or talking during sleep while unaware of doing so. It may be brought on by emotional stress, fever, or another sleep disorder such as sleep terrors, OSA, confusional arousals, or REM-sleep behavior disorder. If other sleep disorders are absent, it is essentially benign. It is seen in all stages of sleep. It is most commonly seen in REM sleep, with an association with dream images.


Nocturnal Leg Cramps: This is painful muscle tightness in the calf or foot during sleep. These cramps lead to arousal or awakening, and if prolonged or frequent, may cause sleep-maintenance insomnia. A formal sleep study is not very useful in this disorder.

Parasomnias linked with REM sleep

These parasomnias are grouped under the same heading because it is suspected that some problem associated with the physical changes seen in REM sleep is the basis for them.


Nightmares: These are frightening dreams that wake a person from REM. They must be carefully examined to differentiate them from night terrors or REM-sleep behavior disorder. They are not usually associated with talking, screaming, hitting, or walking. Certain medications can cause or worsen nightmares (L-Dopa, beta-adrenic blockers, and withdrawal of REM-suppressing drugs). The person is usually fully alert and has full memory of the event once awake. During a sleep study, an abrupt awakening from REM sleep is seen, with an increase in eye movements sometimes seen prior to the awakening.

Sleep Paralysis: In this disorder, a person is unable to move or speak for one to several minutes as they are falling asleep or waking up. Breathing is not affected, but the person may feel it is difficult to breathe as a fright reaction to the situation. Sleep paralysis ends independently or as a result of the person being touched or moved. It is made worse by an irregular sleep schedule, jet lag, shift work, sleep deprivation, stress, and fatigue. In some people, it is more common when they lie on their back.


Impaired or Painful Penile Erections: During sleep, especially REM sleep, males usually have penile erections. These occur cyclically throughout the night. In men with impotence, sleep studies can be performed to determine if the cause is psychosomatic or organic by using additional testing equipment to determine whether erections are occurring, and if so, whether they are adequate for engaging in sexual intercourse. Causes of organic impotence include diabetes, epilepsy, neurologic disease or damage, cancer, decreased testosterone, venous leakage, elevated prolactin, or the use of many prescribed or recreational drugs. It also may result from another sleep disorder, such as OSA, that disturbs or limits REM sleep. Sleep-related painful erections occur during REM sleep but erections are not painful during wakefulness. This is a relatively rare condition. The repeated awakenings can result in insomnia, anxiety, excessive sleepiness, and irritability.

REM Sleep-Related Sinus Arrest: In this disorder, an otherwise healthy, usually young person, has episodes where the heart pauses in beating. These pauses may last close to 10 seconds and occur repeatedly in REM sleep. These pauses are not associated with any pauses in breathing, seizures, arousals or other sleep disorder. Most patients are symptom-free and an EKG during the day is normal. Some patients experience occasional chest tightness, but most do not. Due to potential heart attack, a pacemaker may be implanted.


REM Sleep Behavior Disorder: This disorder usually is not seen until the ages of 45-55, primarily in men. The typical muscle paralysis seen in REM is incomplete or absent, so the person begins "acting out his dreams." The activity is usually very emotionally charged, with hitting, kicking, and crying out seen. Frequently the person, the bed partner, and the surrounding furnishings are hurt. When the person is awakened, they usually report dreams that match the activity.

Other parasomnias

Sleep Bruxism: This is the grinding of teeth at night. It may cause morning headaches, facial pain or jaw pain. There is considerable night to night variability in frequency.


Sleep Enuresis: This is bedwetting that occurs in persons over the age of 5 years. It may be associated with a small or irritable bladder, obstructed breathing, nocturnal seizures, and may be worsened by an allergy to milk. Heredity also appears to be a factor.


Sleep-related Abnormal Swallowing Syndrome: In this disorder, too little saliva is swallowed, leading to an excess that can cause aspiration, coughing, choking, arousals, and awakenings. Gurgling sounds are heard right before the awakening or arousal. Other problems that must be ruled out before this diagnosis is made are: gastroesophageal reflux (GERD), sleep terrors, central sleep apnea (CSA), obstructive sleep apnea (OSA), sleep choking, and sleep-related laryngospasm.


Nocturnal Paroxysmal Dystonia (NPD): This parasomnia involves repeated sustained muscle contractions that cause twisting and repetitive movements or unusual positions during NREM sleep. There are two types seen: short-episode, which lasts from 15-60 seconds, and long-episode, which lasts 1-60 minutes. Short-episode NPD can happen several times during the night (up to 15 times) and usually follows an arousal. When the episode is over, the person is aware and usually falls back to sleep. NPD episodes usually occur out of Stage 2 sleep. EEG shows no seizure activity before or after the event, but some breathing or heart-rate slowing prior to the event may be seen.


Sudden Unexplained Nocturnal Death Syndrome (SUNDS): Because of its specific association with sleep, this is grouped here. It is usually seen in seemingly healthy young Southeast Asian males. Often, the first signs of it are gasping, choking, difficulty breathing without wheezing or sounds of strain during sleep. The person cannot be awakened and ventricular fibrillation then occurs. Those who die from SUNDS often have reported frequent sleep terrors.


Primary Snoring: This is diagnosed when a person has snoring, frequently loud, but no other signs of a sleep-related breathing disorder. No cardiac arrhythmias, oxygen desaturations, snoring-related arousals, or airway obstructions are seen. The patient has no difficulty falling asleep and is not sleepy during the day. Snoring is continuous, typically worse when the person is on his or her back, and the person may awaken with a dry mouth or sore throat. Primary snoring is problematic in that it is also disturbing to bed partners. A sleep study should be performed to ensure that there are no obstructive events or other sleep disruption present.


Benign Neonatal Sleep Myoclonus: This is a problem of muscle jerks that affects the sleep of newborns. The arms, legs, and body are affected by these jerks and they occur in bursts of 4 to 5 jerks lasting approximately 1 second each. They are harmless and usually disappear after a period of several days or months.


Infant Breathing Disorders: This includes the following: Sudden Infant Death Syndrome (SIDS), Infant Sleep Apnea (ISA), Congenital Central Hypoventilation Syndrome, and Infant Sleep-Related Breathing Disorders. The fact that newborns spend so much of their time asleep allows these to be grouped as sleep disorders, but breathing problems in infants are common due to the immaturity of the respiratory system at birth.


Premature infants are at much higher risk for most of these breathing/sleep disorders leading to Apparent Life-Threatening Events (ALTE). However, in all cases, Infant Sleep Apnea caused by an abnormally small airway, and Congenital Central Hypoventilation Syndrome are disorders that fall outside the boundaries of typical and should be treated early and rigorously. The treatment of other infant sleep-related breathing disorders will vary by prematurity, severity, and interpretation by the primary physician. Generally these are monitored until symptoms improve, as there is a presumed but not proven link between apnea and SIDS.