Nonobstructive Pediatric Sleep Disorders

Insufficient Sleep Syndrome

Insufficient sleep is a common cause of daytime sleepiness in children, particularly adolescents. Many children fall short of getting the recommended amount of sleep per 24 hours, which includes naps ( Table 4.1 ). Sleep duration decreases for a variety of reasons as children age, including later bedtimes as a result of watching television or doing homework. In addition, early school start times may contribute to insufficient sleep. The ramifications of insufficient sleep can include behavioral changes, chronic fatigue, missing school, poor school performance, irritability, and driving accidents. In one prospective study, children who experienced insufficient sleep in preschool and the early school years displayed poorer maternal- and teacher-reported executive function, behavior, and social-emotional function at age 7 years than those who slept the appropriate amount. Insufficient sleep can also increase the risk of hypertension, obesity, diabetes, and depression, as well as suicidal thoughts in teenagers. Consequently the American Academy of Sleep Medicine has proposed that school days for middle and high schoolers should begin at 8:30 a.m. or later to promote safe driving, overall health, and better academic performance.

Unfortunately it is quite possible that parents may actually overestimate the amount of sleep their children are getting, because the time of actual sleep onset may be later than the reported bedtime. With this in mind, parents must be vigilant for signs of insufficient sleep syndrome, such as the need to be awakened for school, attempts by the child to catch up on sleep over the weekend, falling asleep at inappropriate times, or behavioral changes. Treatment involves behavioral modifications for both the adolescent and the family, especially if family members subscribe to similar patterns, to reinforce good sleep hygiene for the entire household.

Narcolepsy

Narcolepsy is a rapid-eye-movement (REM) sleep disorder that often starts in adolescence and is classically defined as a combination of irresistible daytime somnolence, sleep onset paralysis, and hypnagogic hallucinations, which are vivid hallucinations on sleep onset. The condition affects approximately 0.02% to 0.05% of the U.S. population, but only approximately 50% of individuals will exhibit the classic triad of symptoms. ^, The ICSD-3 has further subdivided narcolepsy into types 1 and 2. Narcolepsy type 1 is known to be caused by a deficiency of the neurotransmitters hypocretin-1 and -2 (orexin-A and -B), which promote wakefulness and prevent inappropriate transition to non-REM or REM sleep. Narcolepsy type 2 is associated with normal hypocretin-1 levels and is of unknown cause. ^, Patients with narcolepsy type 1 may also display cataplexy, the sudden but brief loss of muscle tone associated with emotional triggers. Evaluation of suspected narcolepsy should include overnight polysomnography (PSG) data to rule out other sleep disorders, followed by a daytime multiple-sleep latency test (MSLT) or analysis of cerebrospinal fluid for hypocretin-1 deficiency. The MSLT is an objective test that measures the speed of falling asleep during 20-minute napping intervals, with a faster onset of sleep indicating a greater level of sleepiness. A child with narcolepsy will often exhibit spontaneous onset of REM sleep during at least two of these naps, whereas healthy participants will exhibit no REM sleep. The diagnostic criteria for narcolepsy (both types 1 and 2) include a sleep latency of less than 8 minutes on the MSLT, whereas normal sleep latency is approximately 15 minutes. Differentiating between narcolepsy types 1 and 2 relies on the presence of cataplexy and on cerebrospinal fluid hypocretin-1 levels, if measured.

Children with narcolepsy may begin having symptoms as early as 5 years of age, but they may not be diagnosed until much later in adolescence because of confounding emotional and behavioral disturbances. ^, Symptoms are often characterized by roughly 10- to 20-minute sleep attacks in which an irresistible urge to sleep invades normal daily activities such as eating, driving, or walking. Cataplexy in addition to intense hypersomnia is pathognomonic for narcolepsy type 1. Adequate treatment of children with narcolepsy is important because these children often manifest increased emotional lability, adjustment difficulty, and problems in school. In addition to promoting good sleep hygiene and establishing healthy sleep-wake schedules, treatment includes stimulants to decrease daytime sleepiness, modafinil to promote wakefulness, and suppression of REM sleep with agents such as tricyclic antidepressants or serotonin reuptake inhibitors. ^, Additional studies are also looking at agents such as sodium oxybate, which acts as an agonist on the γ-aminobutyric acid (GABA) B receptor, to specifically address the cataplexy component of narcolepsy.

Sleep-Related Movement Disorders

It is important to recognize limb movement disorders such as restless leg syndrome (RLS) and periodic limb movement disorder (PLMD) in children, lest associated pain, sleep disturbances, and possible comorbid neuropsychiatric conditions go untreated. RLS is defined as the subjective complaint of uncomfortable tingling sensations in the lower extremities around bedtime with relief of symptoms with movement, whereas PLMD is the repetitive contraction of the anterior tibialis muscle evaluated objectively in the sleep laboratory ( Box 4.1 ). ^, Most patients with RLS will also have periodic limb movements on PSG; however, the converse is not always true. Approximately 2% of the pediatric population surveyed in one study of more than 10,000 families met the criteria for a diagnosis of RLS. No gender differences were observed, and 70% reported a family history of RLS. Sleep disturbances were common in children with RLS, as was the complaint of “growing pains”; therefore RLS should at least be considered and appropriately treated in children with sleep difficulty and unexplained pain. Renal failure and iron deficiency are two comorbidities that are thought to exacerbate pediatric RLS. Dopaminergic dysfunction results from a deficiency of iron in the central nervous system and aggravates symptoms. When ferritin levels are less than 50 μg/L, supplemental iron therapy should at least be considered. Although PLMD may be a benign finding, many children with PLMD exhibit daytime symptoms associated with ADHD and deserve further neuropsychiatric evaluation if clinical suspicion is present. The mainstays of treatment for both RLS and PLMD are dopaminergic therapy, gabapentin, benzodiazepines, and possibly iron therapy. ^,

Sleep-related bruxism is a specific form of sleep-related movement disorder characterized by grinding or clenching of the teeth during sleep, which may result in sleep arousals if severe. The prevalence of bruxism typically decreases with age; however, the persistence of bruxism may be related to separation anxiety in the child and the tendency for the parent to remain in the bedroom until the child falls asleep.

Sleep-related rhythmic movement disorder includes behaviors such as body rocking, head banging, and head rolling, which usually occur at sleep onset and disappear early in childhood. ^, Such behavior is typically benign and should be treated primarily by creating a safe environment for the child. If the behavior persists beyond early adolescence, an evaluation for other neuropsychiatric conditions should be pursued.