Pediatric parasomnias

The word parasomnia derives from the Greek prefix para, meaning alongside of, and the Latin noun somnus for sleep; hence, events that accompany sleep. In the clinical setting, parasomnias are undesirable, nondeliberate events that accompany sleep, over which there is no conscious control. They can involve abnormal sleep-related movements, physical or verbal behaviors, emotions, perceptions, dreaming, autonomic nervous system functioning or a combination of these. They can occur during transition from wakefulness to sleep, within sleep or during arousals from sleep, and they can occur during either daytime naps or regular nighttime sleep. Parasomnias frequently seen in children include sleepwalking (somnambulism), sleep terrors (pavor nocturnus), confusional arousals and nightmares.

Parasomnias are very common in children, can occur in an otherwise "normal" child and usually do not indicate significant psychiatric or psychological problems. They can be triggered or exacerbated when a child is overly tired, has a fever, is taking certain medications or during periods of stress. They may increase or decrease with "good" and "bad" weeks. Parasomnias are clinical disorders because they can result in injuries, sleep disruption, adverse health effects and untoward psychosocial effects. The clinical consequences of parasomnias can affect the child, the child's family or both. The good news is that parasomnias usually are harmless, infrequent and mild. They usually decrease in frequency and intensity as children get older and disappear over time without specific treatment.

Parasomnias are classified according to the stage of sleep in which they originate. Sleep is divided into rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep, which alternate throughout the sleep period. Each type of sleep is associated with distinctive levels of arousal, autonomic response, brain activity and muscle tone. NREM sleep is further subdivided into stages 1, 2 and 3. NREM 3 sleep (previously designated as stages 3 and 4) also is called delta sleep, deep sleep or slow-wave sleep (SWS). The stages represent gradations in depth of sleep and difficulty of arousal – with NREM 1 sleep being the lightest, from which a child can be easily awakened, and NREM 3 being the deepest, from which arousal is difficult and if awakened, the child will appear confused and disoriented. In contrast, children can be easily awakened from REM sleep and  generally are alert and oriented. Dreams occur during both REM and NREM sleep, however, REM sleep is when the most vivid dreams occur. REM sleep dreams appear to be more emotionally charged, complex and bizarre, whereas NREM dreams are more realistic and rational.

The most common explanation for parasomnias is that sleep and wakefulness are not mutually exclusive states and the overlap or intrusion of these states into one another causes these abnormalities. Intrusion of wakefulness into NREM sleep produces disorders of arousal (such as confusional arousals, sleepwalking or sleep terrors), and intrusion of wakefulness into REM sleep produces REM-sleep parasomnias such as nightmares. The International Classification of Sleep Disorders, second edition (ICSD-2) lists 15 types of parasomnias and groups them into three categories:

1. Disorders of Arousal from NREM Sleep (includes sleepwalking, sleep terrors and confusional arousals). These parasomnias usually occur during the first third to first half of the night, often within the first one to two hours after falling asleep, when slow- wave sleep is most prominent. They can last from a few minutes to an hour and are characterized by retrograde amnesia. They usually are associated with agitation and/or confusion and avoidance of comforting measures, which may actually make the agitation worse. There frequently is a genetic component, with 80 percent to 90 percent likelihood that a child with sleepwalking or sleep terrors has an affected first-degree relative. Recent data suggests that they may be more common in individuals with migraine headaches. 

2. Parasomnias Usually Associated with REM Sleep (includes nightmares). These parasomnias usually occur during the last half to last third of the night when REM sleep is most prominent.   

3. Other Parasomnias (includes sleep enuresis, sleep-related eating disorder, sleep-related hallucinations, sleep-related groaning and several others not addressed here).

NREM sleep parasomnias

Sleepwalking is a common and benign parasomnia. Almost 40 percent of all children will sleepwalk at some time, with onset usually between 4 and 6 years old, and peak occurrence between 4 and 8 years old. Adolescents and adults also can experience sleepwalking, particularly if they did so as children. During sleepwalking, the eyes usually are open and although the sleepwalking child may appear to be awake, he or she actually is asleep. The child may appear confused or dazed, and he or she may mumble or give inappropriate or incoherent answers to questions. A sleepwalker often is clumsy and may perform bizarre or strange actions, such as wandering around the house or urinating in a closet. The sleep-walking child should be gently guided back to bed while speaking to him or her in a calm and soothing manner. In general, there is no benefit to trying to wake a sleepwalking child, and it may even result in making the child more agitated or confused and afraid. However, there is no adverse medical effect if he/she does awaken. In the morning, there usually is no memory of these events.

Sleep terrors, or night terrors as they often are called (but which is less accurate as they can occur during daytime naps), usually are the most extreme and dramatic of the parasomnias and can be distressing to witness. Approximately 3 percent of children experience sleep terrors, primarily during the preschool and elementary school years, with onset usually between 4 and 12 years old. The frequency of episodes often is highest at the onset, and frequency tends to be higher when the age of onset is younger. Sleep terrors typically begin suddenly, often with a blood-curdling scream, usually involve crying and/or screaming and frequently are associated with manifestations of extreme agitation and terror including shaking, sweating, tachycardia, hyperventilating and dilated pupils. There may be attempts to escape from bed or to fight, which can result in harm to the child or others. During these events, most children resist being comforted and actually can become more upset and agitated if parents talk to them and try to calm them down. Although a child having a sleep terror may appear to be awake, he or she really is asleep. Sleep terror episodes usually resolve quickly – in three to five minutes – with a prompt return to quiet sleep. Paradoxically, sleep terrors usually are much worse to watch than to experience and much less traumatic to the child than a nightmare or bad dream.

Confusional arousals consist of mental confusion or confused behavior during or following arousals from sleep, typically from slow-wave sleep in the first part of the night, but also upon forced awakening fromsleep during the night or in the morning. These can be similar to sleep terrors but much milder. They often begin with crying and thrashing around in the bed. The child may seem to be awake, but is essentially "stuck" halfway between asleep and awake, usually is very confused or upset and often cries or speaks without making sense. The episodes may appear quite bizarre and frightening to parents, as the child can appear to be "staring right through" the observer. Sometimes there also is yelling or screaming. Confusional arousals usually are short, lasting about five to 15 minutes, but they may last as long as 30 to 40 minutes in some children. It is best for parents to try to resist comforting the child during one of these episodes since most children will become more agitated. Young children who have confusional arousals often go on to have sleepwalking as adolescents.

Sleepwalking and sleep terrors are benign but can lead to physical harm resulting from falling down stairs, walking out of the house or trying to escape. Ensurance of safety should be one of the primary concerns when dealing with these parasomnias. Parents should be instructed to make sure that all outside doors and windows are secured. Tying bells to the child's bedroom door or placing a simple alarm on the door can alert the parent to an event. The sleeping environment should be made as safe as possible to avoid accidental injury, including clearing the floor and stairs of clutter or toys, putting away sharp objects (such as knives and scissors) and securing firearms. If the sleepwalking or sleep terror episodes regularly are occurring at a specific time, briefly waking the child 15 to 45 minutes before this usual time and then allowing him or her to go back to sleep frequently can prevent an event. 

REM sleep parasomnias

Nightmares are frightening dreams occurring during REM sleep that usually result in an awakening from sleep. Nightmares are very common in children and usually are a part of normal development; their content usually differs with the child's age and reflects common developmental issues. Most young toddlers have concerns about being separated from their parents, so they may have nightmares about being lost or having something adverse happen to one of their parents. By 2 years of age, nightmares begin to involve monsters or scary things that can hurt a child. Nightmares are more likely to happen following some difficult event in the child's life (such as starting daycare or a parent going away overnight) or after a frightening experience (such as getting lost, getting a shot at a doctor visit or being barked at by a big dog). Avoiding scary stories, television shows or movies before bedtime can help to reduce the likelihood of nightmares. A child typically is fully awake and alert after awakening from a nightmare. Unlike sleep terrors, parental reassurance and comforting is recommended and usually very helpful, although it may be difficult for the child to go back to sleep. It also can be helpful for a parent to talk to the child about the nightmare the next day to see if there is anything bothering him or her. Most nightmares are isolated events with little significance, but if a child starts having them on a frequent basis, an attempt should be made to try to figure out what may be disturbing the child. (See Table 1 for an overview of common parasomnias.)

Several factors can trigger or exacerbate parasomnias. (See Table 2.) Minimizing these factors is key to the management of parasomnias.

In summary, parasomnias are very common in children and usually do not indicate significant psychiatric or psychological problems. Parasomnias usually are infrequent and mild, and children usually outgrow them. In most instances, no specific therapy or medication is needed except in cases of frequent or severe episodes, high risk of injury, violent behavior or significant disruption to the family. Additional medical evaluation and treatment are indicated if there are symptoms of other underlying sleep disorders (such as obstructive sleep apnea) or concerns about possible sleep-related seizures.

References

Avidan AY, Zee PC. Handbook of Sleep Medicine. Lippincott Williams & Wilkins; 2006: 98-105; 178-181.

Kryger MH, Roth T, Dement WC. Principles and Practice of Sleep Medicine. 4th ed. Elsevier Saunders; 2005: 889-935.

Mindell JA, Owens JA. A Clinical Guide to Pediatric Sleep: Diagnosis and Management of Sleep Problems. Lippincott Williams & Wilkins; 2003: 88-96; 257-263.

Sheldon SH, Ferber R, Kryger MH. Principles and Practice of Pediatric Sleep Medicine. Elsevier Saunders; 2005: 282-287; 293-315.

The International Classification of Sleep Disorders, second  edition (ICSD-2): Diagnostic and Coding Manual. American Academy of Sleep Medicine; 2005: 137-176.

Nan Norins, MD, is a pediatric sleep medicine specialist and a pediatric critical care specialist at Children's Hospital of Wisconsin. She also is an assistant professor of Pediatrics (Pulmonary and Sleep Medicine) at the Medical College of Wiconsin and a member of Children's Specialty Group.

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