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Childhood Sleep Disorders
In this section, I review some of the common sleep disorders of childhood and how they affect families. Developmental failures in achieving consolidated nighttime sleep and daytime wakefulness, in going to bed and falling asleep easily, in maintaining continuity of sleep, and in circadian regulation of sleep-wake cycles are significant risk factors for potential sleep disorders in infants, children, and adolescents. An understanding of childhood sleep disorders is facilitated by knowledge about the development of both sleep-state architecture and sleep-wake-state temporal organization. The maturation of sleep-wake states has been reviewed elsewhere (Anders and Eiben 1997; Coons and Guilleminault 1982), and only a summary is provided here.
Childhood Sleep Disorders
Developmental Aspects of Sleep-Wake Organization
Newborns spend 50% of their sleep time in rapid eye movement (REM) sleep (also known as active sleep or dreaming sleep) and 50% of their sleep time in non-REM (NREM) sleep (also known as quiet sleep or slow-wave sleep). By adolescence, the relative proportion of REM sleep during sleep time has diminished to 20%, whereas NREM sleep has increased proportionally to 80% of sleep time. Four stages of NREM sleep (Stages 1-4) can begin to be differentiated from patterns on the electroencephalogram (EEG) by age 3-4 months. REM and NREM periods alternate with each other in 50- to 60-minute (i.e., ultradian) sleep cycles. A period of 30 minutes of REM sleep is followed by 30 minutes of NREM sleep in a sleep cycle, and three to four sleep cycles constitute a 4-hour episode of sleep for the newborn. At age 3 months, diurnal influences begin to affect sleep-cycle organization (Ferber 1999).
Early sleep cycles have 40-50 minutes of NREM sleep and 10-20 minutes of REM sleep; in sleep cycles later in the night, the reverse is true. Thus, NREM sleep, especially Stage 4 NREM sleep, shifts to the beginning of a sleep period, and REM sleep predominates later in the sleep period. As the continuous periods of sleep consolidate and lengthen, the number of REM-NREM sleep cycles increases.
However, the 50- to 60-minute sleep cycle itself does not lengthen until adolescence, when the 90-minute sleep cycle of mature adults is achieved. Another noteworthy developmental landmark occurs at sleep onset. When young infants make the transition from wakefulness to sleep at the beginning of their night, their initial sleep-onset state is typically REM sleep. By age 3 months, sleep-onset REM periods begin to be replaced by sleep-onset NREM periods. By the time the child is 1 year old, transitions from waking directly to REM sleep are rare.
Appreciating these maturational changes is useful for clinicians in differentiating many of the common sleep disorders that affect infants, children, and adolescents.
Rapid eye movement (REM) sleep
Rapid eye movement sleep, or REM, is one of the five stages of sleep that most people experience nightly....
Sleep disturbances are common in youth, including both medically based (eg, obstructive sleep apnea [OSA], restless leg syndrome, periodic limb movement disorder, and narcolepsy) and behaviorally based (eg, behavioral insomnia of childhood) sleep disorders. Common complaints include trouble falling asleep, night waking, snoring, excessive daytime sleepiness, and poor daytime functioning. These complaints often are signs of treatable sleep disorders. However, several studies found that sleep disorders may be underdiagnosed in pediatric practices.
If sleep disorders are not diagnosed and are left untreated, their negative impact on daytime functioning may be significant.
Studies indicated that most parents do not report significant sleep concerns to their pediatricians.
One study found that 15% of children with current parent-reported sleep disorder symptoms had chart notes indicating those sleep issues. Reasons for this underreporting may include a lack of parent and provider awareness about the serious consequences of insufficient or disrupted sleep and the lack of physician training and comfort with the assessment and diagnosis of pediatric sleep disorders.
Pediatric sleep disorders fall into multiple categories, with varying prevaence rates. Approximately 1% to 3% of children have OSA, whereas 5% to 27% have primary snoring. Behavioral insomnia of childhood, which involves bedtime problems and night waking, affects 20% to 30% of infants and toddlers and up to 5% of school-aged children.
Rates of primary or psycho-physiological insomnia range between 5% and 20%, with rates being higher among adolescents and youths with developmental disorders. Parasomnia rates range from 5% to 35%, depending on the disorder (eg, sleep terrors versus enuresis) and the child's age.
Medical-psychiatric - associated sleep disorders comprise the neuropsychiatric conditions that typically include sleep disturbances. This category has been eliminated in DSM-5 but should still be considered by the clinician when evaluating sleep disorders. The medical differential should include the following:
- Attention deficit hyperactivity disorder (ADHD)
- Gastroesophageal reflux disease (GERD)
- Pervasive developmental disorders
- Mental retardation
- Down syndrome
- Prader-Willi syndrome
- Smith-Magenis syndrome
- Tourette disorder
- Nocturnal asthma
- Depressive disorders
- Anxiety disorders
- Mania
- Neuromuscular disorders
- Nocturnal seizures
- Kleine-Levin syndrome
- Chronic fatigue syndrome
- Headaches
- Blindness with associated sleep disorder
Sleep-related movement disorders (periodic limb movement disorder and restless leg syndrome) are estimated to affect 2% to 8% of youths.
Finally, the prevalence rate of narcolepsy among youths is yet to be determined (the prevalence rate among US adults is 1 case per 2000 individuals), although one-half of adult patients report the onset of symptoms before age 20.
- Nightmares (30%) are more common in younger youths
- Sleepwalking with at least more than 1 episode occurs in 25-30% of youths and is most common in children aged 3-10 years
- Insomnia occurs in 23% of youths
- Enuresis rates decrease from 8% in children aged 4 years to 4% in children aged 10 years
- Bruxism is reported in 10% of youths and may occur in people of any age
- Grinding and clenching teeth at night is reported in 5-8% of adults
- Sleep rocking or head banging is reported in 5% of youths, with head banging being common in infants and in children aged 9 months to 12 years
- OSAS is the most common reason for sleep laboratory referral and affects an estimated 2% of children
- Narcolepsy (0.01-0.20%) may be underestimated in children because a classic tetrad of symptoms is uncommon in this age group; only about 10% of children show all the symptoms: excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis; semipurposeful automatic behavior, disrupted nocturnal sleep, sudden onset of weight gain, obstructive sleep apnea, and, especially, anosmia, should increase clinical suspicion
- Bedtime resistance in school-aged children has been reported at 15% and is often associated with limit-setting disorder
- The results of a population-based study on schoolchildren in Istanbul found that decreased total sleep duration is more prevalent in boys, older children, and children with higher socioeconomic status; insufficient sleep in these groups may be associated with negative behavioral symptoms and sleep hygiene
