Sleep Problems
Judith A. Owens
I. Description of the problem.
A. Sleep problems constitute one of the most frequent parental complaints in pediatric practice.
Childhood sleeplessness, insufficient or disturbed sleep, in its many forms, clearly is a common parental concern.
In contrast, the relationship between sleepiness and its many manifestations is less frequently recognized by parents, but is nonetheless a significant clinical concern. A wealth of empirical evidence from several lines of research clearly indicates that children and adolescents experience significant daytime sleepiness as a result of inadequate or disturbed sleep, and that significant performance impairments and mood dysfunction, as well as behavior, academic, and health problems in childhood, are associated with that daytime sleepiness.
B. Epidemiology.
1. 25% of all children experience a sleep problem at some point during childhood, ranging from short-term situational difficulties in falling asleep, to night wakings, to more chronic and persistent sleep disorders.
2. Although many sleep problems in infants and children are transient and self-limited, the common wisdom that children “grow out of” sleep problems is not an accurate perception. Certain intrinsic and extrinsic risk factors (e.g., difficult temperament, maternal depression, family stress) may predispose a given child to develop a more chronic sleep disturbance.
3. Sleep problems are a significant source of distress for families. There may be, for example, a primary reason for caregiver stress in families with children who have chronic medical illnesses or severe neurodevelopment delays.
4. The impact of childhood sleep problems is intensified by their direct relationship to the quality and quantity of parents’ sleep, particularly if disrupted sleep results in parental daytime fatigue and mood disturbances, which impact negatively on the quality of parenting.
5. Vulnerable populations, such as children who are at high risk for developmental and behavioral problems because of poverty, parental substance abuse and mental illness, or violence in the home, may be even more likely to experience “double jeopardy” as a result of sleep problems.
C. Etiology/contributing factors.
1. Child variables include temperament and behavioral style, individual variations in circadian preference, cognitive and language delays, and the presence of comorbid medical and psychiatric conditions.
2. Parental variables include parenting and discipline styles, parents’ education level and knowledge of child development, mental health issues such as maternal depression, family stress, and quality and quantity of parents’ sleep.
3. Environmental variables include the physical environment (space, noise, perceived environmental threats to safety, room and bed sharing, televisions in the bedroom), family composition (number, ages, and health status of siblings and extended family members), and lifestyle issues (parental work status, competing priorities for time).
4. Cultural and family context, for example, co-sleeping of infants and parents is a common and accepted practice in many ethnic groups (including African Americans, Hispanics, and Southeast Asians) both in their countries of origin and in the United States. Therefore, the developmental goal of independent “self-soothing” in infants at bedtime and after night wakings may not be shared by all families.
5. Specific medical conditions that may have an increased risk of sleep problems include the following:
Asthma and allergies
Headaches
Neurologic disorders and rheumatologic conditions
Children with anxiety and affective disorders are particularly vulnerable to sleep problems. Studies of children with major depressive disorder, for example, have reported a prevalence of insomnia of up to 75%, and sleep onset delay in one-third of depressed adolescents. Use of psychotropic medications in these children may have significant negative effects on sleep.
Significant sleep problems occur in 30% to 80% of children with severe mental retardation and in at least 50% of children with less severe cognitive impairment. Similar estimates in children with autism/pervasive developmental delay are in the 50% to 70% range.
II. Making the diagnosis.
A. Sleep physiology.
1. The framework or architecture of sleep is based upon recognition of two distinct sleep stages. These stages are defined by distinct polysomnographic (or “overnight sleep study”) features of EEG patterns, eye movement, and muscle tone.
REM sleep (rapid eye movement or “dream” sleep). REM sleep (20%-25% of total) is characterized by high levels of cortical activity and low or absent muscle tone.
Non-REM sleep (75%-80% of sleep in healthy young adults). Non-REM sleep is further divided into:
Stage 1 sleep (2%-5%) which occurs at the sleep-wake transition and is often referred to as “light sleep”
Stage 2 sleep (45%-55%) which is usually considered the initiation of “true” sleep and is characterized by bursts of rhythmic rapid EEG activity and high amplitude slow wave spikes
Stages 3 and 4 sleep (3%-23%) which are otherwise known as “deep” sleep, “slow wave sleep,” or “delta sleep,” during which the highest arousal threshold (most difficult to awaken) also occurs
2. Cycling of stages.
Non-REM and REM sleep alternate throughout the night in cycles of about 90 to 110 minutes in adults (50 minutes in infancy and gradually lengthening through childhood to adult levels).
Brief arousals normally followed by a rapid return to sleep often occur at the end of each sleep cycle (4-6 times per night in adults; 7-10 times per night in infants).
The relative proportion of REM and non-REM sleep per cycle changes across the night, such that slow wave sleep predominates in the first third of the night and REM sleep in the last third.
3. Two-process sleep system. Sleep and wakefulness are regulated by two basic highly coupled processes operating simultaneously:
The homeostatic process, which primarily regulates the length and depth of sleep. The homeostatic “pressure” for sleep builds as time awake increases in duration.
Endogenous circadian rhythms (“biological time clocks”), which influence the internal organization of sleep and the timing and duration of daily sleep-wake cycles.
Circadian rhythms (which govern many other physiologic systems in addition to sleep-wake cycles) are also synchronized to the 24-hour-day cycle by environmental cues, the most powerful of which is the light-dark cycle which influences melatonin secretion by the pineal gland.
4. Duration of sleep.
a. Newborns.
Newborns sleep approximately 16 to 20 hours per day, in 1- to 4-hour sleep periods, followed by 1- to 2-hour awake periods.
Sleep-wake cycles are largely dependent upon hunger and satiety. Sleep amounts during the day approximately equal the amount of nighttime sleep.
b. Infants (0-12 months).
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