ABC of Sleep Medicine (ABC Series)

Chapter 8

Sleep Disorders in Children

OVERVIEW

·        Generally, it is parents that recognise and are troubled by sleep-related symptoms rather than the children themselves

·        Poor quality sleep most often leads to daytime behavioural problems rather than excessive daytime sleepiness

·        Normal sleep–wake patterns change rapidly through early childhood

·        Insomnia in young children usually originates from bad habits or routines around bedtime and will, therefore, respond most effectively to behavioural strategies

·        Snoring is not rare in children and might indicate obstructive sleep apnoea (OSA) syndrome in severe cases, necessitating appropriate treatment, most commonly adeno-tonsillectomy

·        In children, OSA can present in several ways and is closely associated with attention deficit disorder and childhood hypertension

·        Persistent and excessive daytime sleepiness at any age during childhood needs to be fully assessed as it usually reflects a formal sleep disorder

·        Parasomnias are extremely common in childhood and usually arise from the deepest stages of non-REM sleep within an hour of sleep onset

·        Nocturnal childhood epilepsy can be distinguished from parasomnia activity in the majority of cases by history alone

What is the problem and whose is it?

As in most areas of medicine, children cannot be viewed simply as ‘little adults’ when assessing and managing sleep-related problems. Firstly, with the exception of nightmares, children rarely complain of sleep disorders themselves. Whether it is excessive snoring or behavioural disturbances at night, it is almost invariably observations from parents that lead to clinical attention. Secondly, the expectations of parents may be inappropriate, especially in the context of infants' sleep patterns. A further potential issue for clinicians involved with children is that sleeplessness might directly reflect the effects of domestic stress or even abuse in a small minority of cases.

With these caveats, however, it is important to stress how chronic bad quality sleep in children might well have profound adverse consequences on the developing brain, body and mind. In addition, the entire family is usually affected by a sleepless child. It is not rare for a worn, haggard parent to seek help for a child who appears ostensibly happy, active, alert and well rested.

As with adults, it is simplest to consider sleep disorders in children as reflecting either insomnia or sleeplessness; excessive or inappropriate sleepiness during the day; or abnormal activities and behaviours from sleep. As with adults, these categories are by no means necessarily mutually exclusive.

Normal sleep in children

Normal patterns of nocturnal sleep in children are clearly heavily influenced by age.

Newborns sleep for up to 18 hours a day with alternating 2–3 hourly cycles of wakefulness and a form of ‘active’ sleep that most closely resembles REM sleep.

By three months of age, the sleep of most babies becomes concentrated at night with 70% sleeping through until morning. Through the first year, overall sleep requirement subsequently declines progressively such that a typical one-year old will require 13 hours.

By one year, non-REM sleep stages start to be easily identified and polysomnographic measures of sleep resemble the adult pattern. Although waking through the night remains extremely common, the important variable in practice is whether the baby quickly returns to sleep when aroused or becomes even more alert and calls out. Around 10% of parents report being routinely awoken through the night by babies at one year.

Co-sleeping with infants is common in many cultures. Potential concerns over damaging or suffocating a small baby have almost certainly been exaggerated in the past. Increasingly, in industrialised populations, it is typical for parents to sleep in separate bedrooms away from young children, predominantly to avoid the absolute need for a parent to be present at any sleep–wake transition. The appropriateness of this strategy is debated, since many parents become excessively attentive to their child when the sleeping environments are separated. Furthermore, the use of intercom units potentially fuels unnecessary parental arousal.

Afternoon scheduled naps are routine at 18 months but usually decline over the subsequent three or four years such that most five- year-olds will be continually awake through the day, typically requiring around 11 hours of sleep. Problems with sleep timing most often arise when social and educational demands are juxtaposed with sleep demands.

The sleepless child

A systematic approach and detailed history, perhaps aided by a questionnaire, is usually helpful in identifying sleep patterns and potentially bad habits or routines. The principles of sleep hygiene in childhood are outlined in Box 8.1.

Box 8.1 Principles of sleep hygiene in childhood

·        The bedroom should be dark and quiet

·        Bedtime routines should be strictly enforced

·        The time of morning waking should be firmly and consistently structured

·        Bedroom temperatures should be kept comfortably cool (around 20°C)

·        Environmental noise should be minimised; occasionally background music may help to block extraneous noise

·        Children should not be hungry before bed; small snacks before bed may be allowed

·        Excessive fluids before bed may interfere with sleep continuity by distending the bladder

·        Children should learn to fall asleep alone

·        Vigorous activity late evening should be avoided

·        A bath can be stimulating for children and may need to be moved to two hours before bedtime

·        Daytime naps should be developmentally appropriate and brief

Behavioural or conditioned factors are far commoner than any formal sleep disorder and will usually respond to a disciplined behavioural approach. In young children, the process of sleep onset needs to be ‘learnt’. Establishing calming bedtime rituals or sleep onset associations is crucial, certainly in the pre-school years. Prolonged nocturnal awakenings requiring the input of a parent to restore sleep are the usual main concern. Strict protocols and adherence to programmes designed to gradually establish sleep onset associations through the night are generally successful, effectively ‘extinguishing’ sleep disruptive behaviours. Positively rewarding ‘good’ nights is also advocated by some.

A common situation arises when babies are given excessive nocturnal fluids overnight such that maladaptive behaviours and bladder distension may fuel the fragmented sleep further. Gradual discontinuation of nocturnal fluids over two weeks is usually effective.

Occasionally, unsuspected medical conditions may cause insomnia secondarily. These include nocturnal asthma, cow's milk allergy, otitis media or other painful disorders. Furthermore, the majority of neurological syndromes affecting young children will have adverse consequences for the sleep–wake cycle. This may require specialist advice regarding pharmacological treatments to aid sleep.

Children diagnosed with attention deficit hyperactivity disorder (ADHD) appear to have disproportionally disrupted sleep. Indeed, some propose that the sleep disruption in these children is the primary problem, fuelling daytime inattention and behavioural abnormalities as secondary features. In particular, as a result of poor quality sleep, children with ADHD might experience unrecognised so-called ‘microsleeps’. Any sleep subsequently accumulated during the day will reduce the sleep drive at night, reinforcing the poor sleep–wake schedule. Although unproven, this speculative interpretation might explain the paradoxical success of stimulant therapy in ADHD. These drugs may eliminate daytime microsleeps, thereby improving both the deficits in attention and the integrity of the sleep–wake cycle.

A common scenario in middle childhood and early adolescence relates to inadequate limit setting, such that a child physiologically prepared for sleep simply refuses to stay in the bedroom. The ensuing struggle with parents may escalate, most often terminating with a parent acceding to the child's wishes and reinforcing the unwanted behaviour. Persistence and consistency with a bedroom ritual, perhaps enhanced by closing a door or gate to the bedroom, rather than punishment or expressions of anger are central to successful behavioural modification in this situation. Social or environmental factors, however, such as sharing a room with a sibling may complicate the issue of limit setting.

A significant proportion of adolescents might be considered ‘night owls’ in that they prefer to stay up late and extend their sleep period to mid-morning or later. Although behavioural or psychosocial factors may clearly fuel this tendency, it is increasingly acknowledged that the typical circadian rhythm of a teenager is delayed compared to adults such that they are, in a sense, ‘programmed’ to sleep and arise later.

A small minority of subjects with this tendency fulfil the criteria for delayed sleep phase syndrome (DSPS), in which the inability to arise at a conventional hour is so impaired as to cause major problems with schooling. Other than the timing, the sleep of these individuals is normal and the problem often resolves at weekends or when an early schedule is unnecessary. It is important to recognise that DSPS reflects a true disorder of circadian timing and not to dismiss the problem simply as reflecting bad habits or indiscipline. Treatments attempting to advance the clock mechanism are often justified although the evidence base is poor. Low dose melatonin (0.5 mg) taken at 9:00 p.m. may help to facilitate sleep onset around 11:00 p.m. whereas bright light or phototherapy immediately on waking, ideally around 8:00 a.m., may enhance morning arousal.

The child that snores

Benign noisy nocturnal breathing is frequently observed in young children and should be distinguished from potentially serious conditions such as obstructive sleep apnoea (OSA) or other breathing-related disorders.

Approximately 10% of five-year-olds will snore most nights without evidence for airway obstruction or sleep fragmentation (primary snoring). However, depending on precise definitions, between 1 and 2% of children will exhibit pauses in their breathing pattern, so-called hypopnoeas or apnoeas, at least five times an hour. Aside from the adverse consequences for sleep quality, secondary effects such as school failure or growth retardation can be profound.

Parents will report a variety of symptoms in children with OSA (Box 8.2). Most describe loud snoring and frequent mouth breathing at night with restlessness and enuresis affecting around 50%. Difficult daytime behaviour is also observed in 50%, with developmental delay in 20%. Overnight, children will often adopt an unusual sleeping posture with their neck hyperextended. Unlike with adults, frank daytime sleepiness is relatively rare in childhood OSA. However, in common with the adult population, increasing evidence suggests a strong correlation between the severity of sleep apnoea and hypertension, particularly systolic blood pressure.

Box 8.2 Typical symptoms reported in childhood OSA

Symptoms at night

Symptoms during day

Snoring

Poor school performance

Witnessed pauses in breathing (apnoea)

Aggressive behaviour

Choking noises

Hyperactivity

Increased efforts to breathe

Attention deficit disorder

Enuresis

Morning headaches or lethargy

Frequent awakenings or restless sleep, often with increased nightmares

Excessive daytime sleepiness (surprisingly rare)

Dry mouth in morning

 

Increased sweating

 

Abnormal posture in sleep (typically hyperextended neck)

 

Although largely a clinical diagnosis, childhood OSA should be confirmed by overnight oximetry and, ideally, other measures of breathing parameters either in the home or in a hospital setting (Figure 8.1). Given the spectrum of severity of airways obstruction in children (Figure 8.2), deciding when to treat can be difficult. In the absence of clear guidelines, clinical impression is usually the main arbiter in practice.

Figure 8.1 Oximetry trace of 4 year-old child with severe OSA recorded over a night (time shown on horizontal axis). Repeated dips in oxygen saturations below 60% are seen during nocturnal sleep (vertical axis). These most likely coincide with REM sleep episodes when snoring and apnoeas are generally more pronounced because muscle tone is decreased.

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Figure 8.2 The spectrum of obstructive sleep-disordered breathing in children.

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OSA in children is most commonly treated effectively by adenotonsillectomy, which improves sleep parameters in almost 90% of cases. There is often an associated growth spurt after the operation. This presumably reflects restoration of growth hormone secretion, which occurs in the first hour of deep non-REM sleep in children. There is also evidence that school performance may be enhanced a year after successful treatment of OSA.

There may be other reasons for a narrowed airway that need addressing, such as severe obesity or a receding chin (retrognathia). The latter may reflect an underlying congenital problem such as Pierre Robin syndrome. Regarding obesity, for every unit increment of body mass index (BMI) beyond the mean, the OSA risk increases by 12% in children. A number of complex childhood syndromes may produce significant sleep-related breathing problems that may go unrecognised but require specialist treatment (Box 8.3).

Box 8.3 Examples of complex syndromes in childhood associated with sleep-related breathing disorders potentially requiring specialist input

·        Achondroplasia

·        Asperger's syndrome

·        Arnold–Chiari malformation

·        Downs syndrome

·        Hirschsprung's disease

·        Mucopolysaccharide storage disorders

·        Pierre Robin syndrome

·        Prader–Willi syndrome

·        Syringomyelia

Rarely, snoring may be mistaken for other noisy phenomena at night, such as wheezing or stridor. The former may be limited to the nocturnal period, usually with an accompanying cough and most often indicates asthma. The latter may be seen with structural vocal cord or laryngeal pathology, potentially following any prolonged period of intubation in children. Severe acid reflux at night in children is also rare but may present as a nocturnal breathing difficulty.

The sleepy child

If young children are observed regularly falling asleep in inappropriate situations, it usually indicates a significant sleep disorder justifying further assessment and possible treatment. Even in the absence of frank napping, daydreaming reported by teachers or increased motor activity and distractibility can all reflect manifestations of sleepiness in childhood. The most important diagnoses not to miss are breathing-related disorders such as sleep apnoea (see above) or primary central nervous system sleep disorders such as early onset narcolepsy or idiopathic hypersomnolence.

Narcolepsy most commonly starts in adolescence but is often missed and only diagnosed years later. Indeed, one-third of patients retrospectively report abnormal sleepiness that started before the age of 15. Young narcoleptics may also develop an intense fear of going to bed due to intrusive REM sleep phenomena, including sleep paralysis and vivid nightmares. This may be misinterpreted as simple night terrors. Furthermore, in childhood, cataplexy may be subtle and atypical. For example, facial grimacing and tongue protrusion is commonly seen as a response when children try and overcome focal facial weakness during emotional episodes.

Although relatively rare, conditions such as restless legs syndrome or other causes of secondary insomnia, including chronic pain, should not be overlooked as potential causes of excessive daytime sleepiness in children.

One extremely rare cause of intermittent profound sleepiness that can be seen in teenagers is Kleine–Levin syndrome. In this, subjects appear extremely somnolent for continuous periods lasting up to a fortnight. A frequent additional feature is a personality change and inappropriate behavioural responses whilst symptomatic. Overeating or hypersexuality are typical examples. Episodes typically occur every few months with a normal sleep–wake cycle in between. Diagnosis is largely clinical and treatments remain empirical although some benefit from intermittent stimulant therapy.

Parasomnias in children

Parasomnias arising from deep non-REM or slow wave sleep are extremely common in children, affecting up to 15% on a regular basis. These phenomena are often termed ‘arousal disorders’, since they usually reflect abnormal partial arousals from the first period of deep sleep. They generally occur within an hour or two of sleep onset and produce a range of behavioural phenomena from simple confusional arousals to agitated night terrors and frank sleepwalking. Adjustments to the sleeping environment to avoid injury may be justified but long-term drug treatment is rarely appropriate. Spontaneous resolution through adolescence is usually seen although persistence of the phenomenon may occur in at least 2% of the adult population.

It is not uncommon for frequent parasomnia activity to be mistaken for possible nocturnal epilepsy. Most cases can be diagnosed with confidence from a thorough history, if available (Table 8.1). In selected cases, prolonged video-polysomnography is necessary to aid differential diagnosis.

Table 8.1 Some distinguishing features of parasomnias compared to nocturnal (partial) seizures, usually arising from the frontal lobe.

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Sleep-related enuresis is usually considered abnormal if seen beyond five years of age and can divided into primary or secondary forms. The former refers to involuntary discharge of urine during sleep present continually since birth. The latter is said, somewhat arbitrarily, to occur if there has been a dry spell of at least three months and is more often linked to organic or psychological fuelling factors. Although it is often assumed that children with primary enuresis sleep more deeply than average, it is not clear whether abnormal sleep architecture or faulty control of bladder mechanisms prevail in individual cases.

A variety of behavioural techniques to modify the problem have been developed. Enuresis alarms and fluid restriction have most commonly been advocated. Spontaneous improvement of 15% of cases per year between 5 and 16 years would be expected. Important secondary causes to be considered include unsuspected urinary tract infections, polyuria due to diabetes and obstructive sleep apnoea. Enuresis is commonly seen in children with significant parasomnia activity but is very rarely an isolated symptom of nocturnal epilepsy.

Head-banging can be considered as a parasomnia at the wake–sleep transition affecting around 5% of young children. It is commoner in males and those with learning disability. It is best viewed as a comforting mechanism, partially under voluntary control, to aid sleep onset. Most commonly it resolves with age and needs no special intervention other than adjusting the safety of the sleeping environment. Body rocking at sleep onset is a related phenomenon and similarly usually requires no treatment.

Further reading

Ali, N.J., Pitston, D.J. and Stradling, J.R. (1993) Snoring, sleep disturbance, and behaviour in 4–5 year-olds. Arch Dis Child68, 360–366.

Guilleminault, C., Palombini, L., Pelayo, R. et al. (2003) Sleepwalking and sleep terrors in prepubertal children: what triggers them? Paediatrics111, e17–25.

Konofal, E., Lecendreux, M. and Cortese, S. (2010) Sleep and ADHD. Sleep Med11, 652–658.

Kotagal, S., Hartse, K.M. and Walshe, J.K. (1990) Characteristics of narcolepsy in pre-teen children. Pediatrics85, 205–209.

Sheldon, S.H., Ferber, R. and Kryger, M.H. (2005) Principles and practice of pediatric sleep medicineElsevier Saunders.



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