1. Aetiology and epidemiology
Sleep disorders are common and experienced by 20-30 per cent of children aged one to five worldwide. Disturbed or insufficient sleep has been implicated in disruptive behaviour, attention problems, including ADHD, and children with physical or learning disabilities.
The different types of sleep disorder are listed in the box. Special paediatric designation is given to three conditions: behavioural insomnia of childhood, obstructive sleep apnoea in children, and primary sleep apnoea of infancy.
Insomnia includes difficulty falling asleep or staying asleep, and is estimated to occur in 10-30 per cent of children. Insomnia is a major problem in children with intellectual and other developmental disabilities.
Sleep-related breathing disorder occurs in about 2 per cent of otherwise normal children, commonly in the preschool-age child.
Children with craniofacial abnormalities, neuromuscular disorders and Down's syndrome are particularly vulnerable to complete or partial upper airway obstruction in sleep.
Hypersomnias may be chronic (excessive daytime sleepiness daily for at least three months) or episodic.
In children with episodic sleepiness, pretend sleep in the older child and drug toxicity in the younger child should be considered. Idiopathic narcolepsy syndrome is important to diagnose early, as this has a huge impact on the child's development.
Circadian rhythm disorders include delayed and advanced sleep phase syndromes.
Delayed sleep phase syndrome coexists with ADHD, when the contribution of stimulant medication should be considered. Non-24-hour circadian rhythm is common in blind children.
Parasomnias are undesirable physical events or experiences that occur during entry into sleep, within sleep or during arousals from sleep.
The most common in children are those occurring on abrupt arousal from deep non-REM sleep, including night terrors, starting at 18 months of age, and sleep walking in the slightly older child.
The most common REM sleep parasomnia is nightmare.
Types of sleep disorder
- Sleep-related breathing disorders.
- Hypersomnias not due to circadian rhythm disorders, sleep-related breathing disorders or other causes of disturbed nocturnal sleep.
- Circadian rhythm sleep disorders.
- Sleep-related movement disorders.
- Isolated symptoms, normal variants and unresolved issues.
- Other sleep disorders.
A detailed sleep history, combined with developmental, psychosocial and family history, is essential and may be sufficient for diagnosis. Sleep questionnaires and sleep diaries are popular but should only be used as an adjunct.
Developmentally normal babies and preschool children who do not sleep do not usually require special sleep studies.
It is important to make sure that the night awakenings with distressed crying are not night terror waking.
Sleep disturbance in the child with neurological and developmental disorders may occasionally need investigations as they may have other medical conditions with the potential to disrupt sleep, such as epileptic seizures or obstructive sleep apnoea.
Circadian rhythm disorder
Circadian rhythm disorder should be considered in the older child or adolescent with sleep-onset insomnia if it persists after sleep hygiene implementation. The disorder is best assessed by actigraphy, a non-invasive movement monitor worn on the wrist, providing information on sleep-wake schedules for one to three weeks or longer if this is necessary.
Polysomnography studies are usually not required for sleep-wake transition or non-REM arousal parasomnias. If obstructive sleep apnoea is a possibility, studies measuring nasal air flow, thoracic/abdominal respiration and oxygen saturation, usually with video of night sleep and recording of snoring (limited polysomnography) are carried out.
If the apnoea is from enlarged tonsils and adenoids and there is delay in arranging sleep studies, a referral to ENT may be appropriate.
To assess non-respiratory causes for sleepiness such as narcolepsy, all night polysomnography with EEG is essential, followed by the multiple sleep latency test (MSLT).
The MSLT objectively measures the propensity to fall asleep in a sleep-inducing environment.
In the presence of definite cataplexy episodes in a child with excessive daytime sleepiness, the diagnosis of narcolepsy can be made clinically without sleep studies, although these are still recommended.
Sleep studies are essential to diagnose narcolepsy without cataplexy.
Current evidence suggests that narcolepsy with cataplexy is associated with loss of hypothalamic neurons containing the hypocretin peptide important for wakefulness.
Measuring CSF hypocretin level <110pg/ml in narcolepsy with cataplexy is an alternative to sleep studies.
Behavioural intervention remains the mainstay of treatment for the developmentally normal preschool child who has difficulty settling to sleep or who wakes frequently, after excluding any medical conditions that may disrupt sleep.
Many studies have shown that behavioural intervention can be successful even in the child with severe learning difficulties, including autism, provided the parents are supported by health professionals.
Hypnotic medication should be only a short-term option, bearing in mind that children with learning difficulties may show a paradoxical hyperactivity response to hypnotics.
Many paediatricians prescribe large doses of melatonin for insomnia in children with neurodevelopmental abnormalities and learning difficulties. Melatonin does not have a product licence in the UK although it can be obtained on prescription. It is effective in some children. However, the long-term safety of melatonin is not known and it should be avoided in developmentally normal children, except in very low dosage and for limited period when a sleep-wake cycle disorder has been confirmed.
Adeno-tonsillectomy and treatment to keep nasal passages clear is usually the first intervention in children with sleepiness from upper airway obstruction. Depending on the severity of residual symptoms, interventions including weight loss and continuous positive airway pressure (CPAP). Occasionally wake-promoting medication, such as modafinil, may have to be considered.
The treatment goal for children with narcolepsy is improvement of symptoms so that the child can achieve their maximum educational potential and continue to develop emotionally and socially. If this goal can be met, some parents may prefer to defer regular medication until the late teens, when medication must be considered if the young person wants to drive.
Non-drug measures include ensuring the child gets sufficient night sleep despite disturbed night sleep pattern, weight control, encouraging physical exercise, avoiding high carbohydrate meals during the day and if possible breaking the day with 15-20 minute naps. Close liaison with school is essential.
Medical management should initially focus on improving daytime alertness, which may in some children also reduce cataplexy episodes.
Sleep-wake cycle disorders
In delayed sleep phase syndrome low-dosage melatonin can be used to advance sleep onset, as well as morning bright light therapy.
In those young people with sleep onset occurring in the early hours of the morning, a chronotherapy programme can be trialled with progressive advancement of bed time by three hours a day over seven days, until the desired bed time is reached. This must be consolidated by fixing the morning wake-up time.
In young people who have total loss of entrainment of the 24-hour rhythm, with progressive advancement of bed time, including blind children, long-term treatment with melatonin is the only effective treatment.
Most parasomnias in the pre-adolescent child are self-limiting; reassurance and discussing safety issues may be sufficient, provided intrinsic triggers for arousal such as obstructive sleep apnoea are excluded clinically or through sleep studies.
Sleep hygiene, including strategies to create closure of daytime activities and plans for the next day before entering the bedroom, should be encouraged, as well as avoiding hyper-arousing activities before bed time.
Psychological factors are important to explore in older children. Very occasionally, low-dosage clonazepam maybe prescribed to cover vulnerable periods.