What may seem to be an uninterrupted sleep period is actually made up of a series of 60- to 90-minute cycles, with periods of both non–rapid eye movement (non-REM) and REM sleep. Although these cycles seem uniform and woven together, a child normally experiences five to ten brief, behavioral arousals during the night despite being observed to apparently sleep through the night. In sleep disorders, these underlying patterns may be disrupted with wake-to-sleep transition problems, difficulty in shifting from one sleep stage to another, and failure to return to sleep after a brief arousal. The development of sleep is related to age; the total amount of sleep decreases as children become older, as does the total amount of REM sleep and the total amount of stage 3 to 4 (deep) sleep. Sleep in premature infants is marked by more wakefulness than in full-term infants, with more irregularity and instability in the sleep–wake mechanism. In infancy, the amounts of REM sleep or active sleep are substantially greater than they are later in life, with almost 50% of the infant’s time in the first week of life being spent in REM sleep. Gradually, the REM sleep cycles are shifted so that most REM sleep occurs in the second half of the night.

As children grow older, separation anxiety becomes more of an issue for toddlers and young children, and bedtime fears, nightmares, bedwetting, and night terrors emerge. The older group, particularly the adolescent, begins to show sleep patterns similar to those of adults. Difficulty falling asleep, waking during the night, difficulty getting up in the morning, and daytime sleepiness are commonly reported in adolescence. Individual differences in sleep requirements and patterns occur among children, so rigid sleep schedules may complicate bedtime difficulties and sleep problems.

During the first year of life, after the establishment of a full-night sleep pattern, a period of wakefulness occurs at approximately 9 to 11 months of age, followed by the reestablishment of a full-night sleep pattern. In toddlers, the major difficulties are in settling down to sleep and in nighttime waking. In the preschool child, problems with extensive bedtime routines and resisting falling asleep are common. One study found that two-thirds of normal 5-year-old children require more than 30 minutes to fall asleep.

In the grade-school years, parents often note restless sleep. Sleep-related problems are increased when children develop ear, nose, and throat symptoms. Children with emotional and behavioral difficulties have significantly higher numbers of sleep complaints. Achenbach found that clinically referred children had higher rates of nightmares, excessive tiredness, excessive sleep, difficulty with sleeping, and too little sleep compared with normal children. Simeon found, in a sample of 962 normal children and 103 child psychiatry patients, that sleep talking, difficulty falling asleep, night waking, and enuresis, as well as being overtired, were three times higher among patients than in the normal group. Poor or restless sleep was six times as frequent.

Gender differences were not noted among normal children, but large differences were noted between boys and girls in the psychiatric population, with boys having more sleep talking, enuresis, early morning waking, and daytime naps. Girls reported more restless sleep, night waking, and poor sleep. Therefore, both normal and behaviorally disturbed children have a variety of sleep problems. Furthermore, an association exists between frequency of sleep problems and psychological and behavioral disorders.

The classification system for sleep disorders deals with chronic disorders, not transient disturbances that are part of everyday life. Sleep problems lasting a few nights after a psychosocial stressor are not diagnosed as sleep disorders. Children who are chronically symptomatic for more than a month, however, require further assessment for diagnosis and treatment.

Problems in sleep accompany both mental and physical disorders, particularly conditions involving changes in mood and those causing pain or discomfort. Sleep disturbances may occur at the beginning of an illness and can exacerbate other
disorders. If sleep disturbance is the predominant complaint, however, sleep disorder is the primary diagnosis.

The two major groups of sleep disorders are the dyssomnias and the parasomnias. In dyssomnia, the primary difficulty and disturbance is in the quality, timing, or amount of sleep. In parasomnia, the primary disturbance is an abnormal event that occurs during sleep. Other conditions, such as sleep apnea, which is associated with increased daytime sleepiness, and narcolepsy, are classified as hypersomnias related to a known organic factor. Nocturnal enuresis occurring in the first third of the night and associated with sudden arousal from sleep may be regarded as a sleep disorder. A primary sleep condition independent of known mental or physical conditions would be considered a primary insomnia or hypersomnia.

Included among the dyssomnias are insomnias, hypersomnias, and circadian rhythm sleep (sleep–wake schedule) disorders. In insomnia, sleep is deficient in quality or in an amount necessary for normal active daytime functioning. In hypersomnia (excessive daytime sleepiness), the individual feels excessively sleepy during the daytime despite apparently normal sleep length. In circadian rhythm sleep disorders, the person’s sleeping and daytime waking pattern is different and is not in keeping with an appropriate day–night routine for the environment.

Insomnia includes a complaint of difficulty in both initiating and maintaining sleep or of not feeling rested after sleep that is apparently adequate. Diagnostic criteria for primary insomnia are shown in Box 109.1. To make the diagnosis, the sleep problem must occur at least three times a week for at least 1 month and must lead to complaints of daytime fatigue or observations by others of symptoms related to sleep, such as irritability. It may be primarily related to a known organic factor or related to a nonorganic mental disorder.

Considerable variation exists in the amount of time it takes for a person to fall asleep or in the amount of sleep that an individual feels is needed to be alert and rested. Ordinarily, sleep begins within 30 minutes after establishing a setting that is appropriate for sleep, although sleep length is variable depending on age. Insomnia may be complicated by treatment with pharmacologic agents such as sedatives or hypnotics. It occurs more often after periods of stress and is related to behavioral or emotional symptoms.

With childhood-onset insomnia, it may take longer to fall asleep, and the sleep may be ill defined and associated with an atypical electroencephalographic (EEG) abnormality. In adolescents, the complaint may be difficulty in falling asleep or premature wakening. In other instances, a delayed sleep phase syndrome may be present in which sleep onset difficulties are associated with difficulty waking in the morning. If the individual is allowed to continue to sleep, however, he or she sleeps a normal number of hours. Price found that normal eleventh- and twelfth-grade students reported a 12.6% incidence of severe sleep disturbance. Those with sleep problems also reported more tension, worries, moodiness, and difficulty with solving personal problems, as well as low self-esteem.

Insomnia may occur in conjunction with other mental disorders such as depressive disorders, anxiety disorders, and adjustment disorder with anxious mood or obsessive-compulsive personality. As noted, insomnia also may occur because of a known organic factor, such as a specific medical condition and the use of psychoactive drugs. These disorders are generally symptomatic when the patient is awake or asleep, as in the case of pain. Some physical disorders seem symptomatic only during sleep, however, as seen in sleep apnea, in which waking respiration is normal. Drugs commonly influencing sleep are amphetamines or other stimulants, corticosteroids, and bronchodilators. Psychoactive drugs and alcohol or amphetamine dependence may disturb sleep as well.

In primary insomnia, the individual frequently worries about not being able to fall asleep at night, and this may become a preoccupation. The individual’s worries about unsuccessful attempts to fall asleep increase arousal. However, he or she might be able to fall asleep when not trying to sleep (e.g., while watching television or when away from the usual environment).

Children and adolescents with excessive daytime sleepiness or somnolence may be thought to be inattentive and be labeled as lazy or poor learners. These symptoms may be a consequence of insufficient nighttime sleep, sleep quality, or circadian factors. Sleep apnea may be an unrecognized cause of disrupted sleep. Complaints of sleepiness sometimes are minimized by clinicians. The onset of excessive daytime sleepiness often first occurs during adolescence. A careful physical examination and sleep history are important.

Diagnostic criteria for primary hypersomnia are listed in Box 109.2. The primary features are excessive daytime sleepiness or sleep attacks (not accounted for by inadequate amounts of sleep), or prolonged transition into a fully awake state when awakening (sleep drunkenness). The condition occurs every day for at least 1 month or episodically for longer periods of time and is severe enough to interfere with social activities, relationships, and school. Hypersomnia disorders may be primary or related to nonorganic mental factors or organic conditions. Daytime sleepiness is defined as falling asleep easily, often in 5 minutes or less, at any time during the day, even after a normal, prolonged amount of night sleep. Falling asleep is unintentional, making sleep attacks discrete periods of sudden irresistible sleep. Ordinarily, hypersomnia is present every day, most commonly related to sleep apnea or narcolepsy. It may be episodic in the Kleine-Levin syndrome and in atypical forms of depression.

The course of this condition is related to the presence of other associated physical or mental disorders or to the primary
condition. Social and occupational impairment may be mild or severe. Individuals with these problems may become demoralized, and the complications of accidental injury may ensue because of the excessive sleepiness.