CHAPTER 30

Sleep: Normal Patterns and Common Disorders

Geeta Grover, MD, FAAP, and Thusa Sabapathy, MD

Sleep disorders are common during infancy, childhood, and adolescence. Getting children to go to bed, fall asleep, stay asleep, and stay in bed can be no small challenge. Parents frequently ask pediatricians about sleep-related problems at routine health maintenance visits. Age-appropriate suggestions on how to help children sleep well are usually welcomed by parents.

Epidemiology

Sleep problems occur in 20% to 30% of typically developing children and are among the most common concerns encountered in pediatric practice. Behavioral sleep problems, including bedtime refusal or resistance, delayed sleep onset, and prolonged night awaking requiring parental intervention, are the most common reasons for sleep concerns. Inadequate sleep in children negatively affects the quality of life of both the children themselves and their parents. Increased risk for obesity, mood and behavior problems, as well as impaired concentration and academic failure are some of the consequences associated with insufficient sleep in children.

Higher than normal rates of sleep disturbances are seen in children with medical, neurodevelopmental, and psychiatric disorders, such as obstructive sleep apnea (OSA), autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), intellectual disability, anxiety, and depression. An estimated 25% to 50% of children with ADHD have sleep problems, especially difficulties in initiating and maintaining sleep. The relationship of ADHD and sleep problems is often complex and multidirectional. Children with ADHD have significant symptoms of impulsivity and hyperactivity that can make settling down for bed difficult. In addition, psychostimulant use has been associated with disturbed sleep; interestingly, however, it also has been shown to have the paradoxical effect of regulating children with ADHD and getting them ready for sleep.

An estimated 50% to 80% of children with ASD experience sleep-related difficulties. In typically developing children, behavioral reasons are the most common causes of insomnia. In children with ASD, however, insomnia is multifactorial. In these children, insomnia is the result of behavioral issues; medical, neurologic, and psychiatric comorbidities; and the secondary effects of medications used to manage the symptoms of ASD and the associated comorbidities.

In most Western countries, children are expected to sleep in their own beds. In many cultures, however, it is not uncommon for newborns, infants, and young children to sleep in their parents’ bed (ie, the “family bed”). Bedsharing with newborns and infants younger than 10 to 12 weeks is associated with a higher incidence of sudden unexpected infant death, especially if the mother smokes. Accidental asphyxia from overlaying or the presence of soft bedding or overheating may contribute to bedsharing–related deaths. Parents should always be advised about safe sleeping practices (see Chapter 72). In older infants and children, co-sleeping is not a problem in and of itself, and the decision to co-sleep, like the decision to breast- or bottle-feed, is an entirely personal one. Most newborns and infants who share a bed with their parents have sleep-onset associations that facilitate falling asleep. Therefore, parents who share a bed with their young children commonly must lie down with them for 20 to 30 minutes to get them to fall asleep. Several studies have shown that co-sleeping infants are 2 to 3 times more likely to experience night awaking than those who sleep alone. Furthermore, newborns and infants who are breastfeeding and bedsharing sleep the shortest periods before awaking. Parents who plan to co-sleep with their newborns and infants for only a limited period must develop a clear transition plan, such as ending this practice by 5 to 6 months of age, before infants are old enough to object excessively. For children with sleep problems, bedsharing is not a good solution. In the absence of preexisting sleep problems or psychological concerns, however, co-sleeping as a lifestyle choice has not been associated with any long-term developmental, behavioral, or psychological problems in the co-sleeping children.

Clinical Presentation

Parents may raise concerns about their child’s sleep pattern during a routine health maintenance visit. However, many parents may not volunteer information about their children’s sleep or may not appreciate the potential relationship between sleep problems and daytime behaviors, learning, attention, or overall health. Thus, it is important for health professionals to routinely screen children for sleep disorders.

Pathophysiology

To understand disturbances associated with sleep, it is necessary to understand the physiology of normal sleep and the development of normal sleep behavior in children.

Sleep States

Normal sleep has 2 distinct states—rapid eye movement (REM) and non–rapid eye movement (NREM) sleep. Rapid eye movement sleep develops at approximately 29 weeks of gestation and persists throughout life. It is an active, lighter stage of sleep that occurs in association with rapid eye movements. Other features of REM sleep include suppression of muscle tone; rapid, irregular pulse and respiratory rate; and body twitches. Dreams occur during REM sleep. The pattern of REM sleep noted on electroencephalography (EEG) is very similar to stage 1 NREM sleep.

Non–rapid eye movement sleep begins at approximately 32 to 35 weeks of gestation. During NREM sleep, pulse and respiratory rates are slower and more regular and body movements are minimal. Most of the restorative functions of sleep occur during this state. After the first several months after birth, NREM sleep may be divided into 3 stages. Stage 1 includes drowsiness and the beginning of sleep with slow eye movement. Stage 2 is sleep without eye movement. Stage 3 is deep sleep (also called slow-wave sleep). Each stage represents a progressively deeper state of sleep and has a characteristic EEG tracing.

The Sleep Cycle

Rapid eye movement and NREM sleep together make up the sleep cycle. Typically, the deepest sleep takes place during the first several hours of the night, with lighter stages of NREM and REM sleep occurring during most of the rest of the night. Although sleep stages are the same in infants and adults, several differences exist between the onset and duration of REM and NREM sleep in infants and adults. First, the sleep cycle is shorter in infants than in adults (50–60 minutes and 90–100 minutes, respectively), which means that infants have more periods of active REM sleep than adults. Second, the total amount of time spent in REM sleep decreases with increasing age. Full-term newborns spend approximately 50% of their total sleep time in REM sleep, whereas for preterm newborns up to 80% of total sleep time is spent in REM sleep; this decreases to approximately 30% by 3 years of age and to 20% by adulthood. Third, infants may have very little REM latency, entering their first REM cycle very shortly after falling asleep. Adults, in comparison, generally enter their first REM period approximately 90 minutes after the onset of sleep.

Melatonin, a hormone released by the pineal gland, regulates the sleep-wake cycle. It is often called the “Dracula of hormones” because peak levels occur at night. It has both hypnotic (ie, sleep promoting) and chronobiotic (ie, sleep phase-shifting) effects on the sleep-wake cycle. After melatonin is released into the bloodstream, it is taken into tissues expressing the receptors specific for melatonin and signals the body to prepare for nighttime. The pineal gland is under the control of the suprachiasmatic nucleus, which resides in the hypothalamus. When humans are exposed to light, a signal from the retina is sent to the suprachiasmatic nucleus and subsequently to the pineal gland, thereby suppressing release of melatonin.

Sleep-Wake Patterns

Sleep patterns follow a normal developmental sequence in children, and the amount of sleep children need changes with maturation (Table 30.1). Through age 12 months, infants sleep 12 to 16 hours a day. Many infants can sleep through the night (≥5 hours uninterrupted) by age 3 months, and most infants are capable of this by age 4 months. Brief arousals are a normal part of the sleep cycle at all ages, but children should be able to return to sleep on their own without requiring parental attention. Children should be able to fall asleep on their own by age 4 to 6 months. Otherwise, parental participation to fall asleep becomes required at every awaking throughout the night.

Adapted with permission from Paruthi S, Brooks LJ, D’Ambrosio C, et al. Recommended amount of sleep for pediatric populations: a consensus statement of the American Academy of Sleep Medicine. J Clin Sleep Med. 2016;12(6):785–786.

One- to 2-year-olds sleep 11 to 14 hours per day, and by age 3 to 5 years, children sleep a total of 10 to 13 hours per day. One-year-olds take 2 naps per day. This typically decreases to 1 afternoon nap by 18 to 24 months of age. Most children take an afternoon nap until 3 years of age, and some children continue this until 5 years of age. The amount of nighttime sleep children need continues to gradually decline, decreasing from approximately 12 hours during the preschool years to approximately 8 to 10 hours during adolescence.

Adolescents are often chronically sleep deprived because of a combination of biologically driven processes and modern lifestyle demands (eg, digital media use, excessive extracurricular activities). Biologically, around the time of pubertal onset, adolescents begin to experience changes in their circadian rhythm, with delay of sleep onset and wake times by up to 2 hours (ie, sleep-wake phase delay). It has been suggested that this occurs because of delayed melatonin secretion, as well as slower accumulation of sleep drive, resulting in inability to fall asleep at an appropriate bedtime. In addition, teenagers have more demands and expectations in the late afternoon, including homework and extracurricular activities, that push their bedtime later. Ultimately, adolescents are not getting the recommended 8 to 10 hours of sleep per night, which can have serious consequences, including impaired driving, academic decline, and depression. Emerging studies have demonstrated that early middle school and high school start times can interfere with total nighttime sleep in adolescents. The American Academy of Pediatrics supports delaying start times in middle schools and high schools to relieve sleep deprivation in adolescents and its associated effects. Discussion of the pathophysiology of sleep is incomplete without inclusion of the effect of electronic media. Use of electronic media in the evening hours can disrupt sleep-wake patterns because of several reasons. Media use may directly displace sleep time. Media content may cause physiologic arousal, making it difficult to fall asleep and negatively affecting overall quality of sleep. Additionally, the light emitted by the devices themselves may disrupt circadian rhythms by suppressing endogenous melatonin secretion, making it difficult to fall asleep at the desired bedtime.

Sleep Abnormalities

The etiology of sleep disorders can be complex, involving the interaction of children’s temperamental characteristics, psychosocial stressors in the home, parental child-rearing philosophies, and the developmental nature of normal sleep states and sleep cycles.

Differential Diagnosis

The differential diagnosis of sleep disorders may be distinguished by problems associated with falling asleep or maintaining sleep (eg, frequent night awaking) (Box 30.1). Falling asleep may present 2 types of difficulties: problems associated with settling children to sleep and bedtime refusal.

Inappropriate sleep-onset associations and poor or inconsistent parental limit-setting are the most common reasons for difficulty settling infants and children to sleep. Inappropriate sleep-onset associations in infants are characterized by prolonged night awaking episodes that require parental participation (eg, holding, rocking, feeding) to fall asleep. They have not learned the critical skills of self-calming and initiating sleep on their own. Because these infants do not have the self-soothing behaviors necessary to fall back to sleep after normal nighttime arousals, they also may experience nighttime awaking. Brief arousals are a normal component of sleep. Nighttime awaking is different because of the need for parental participation to resettle the infant. The problem is the difficulty that infants experience falling back to sleep on their own, not the awaking itself.

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