Psychiatrists are waking up to the world of sleep and behavior. Just as the biological revolution witnessed a collapse of barriers between the physical and the mental, so the boundary between sleep and wakefulness is crumbling. The emerging discipline of sleep medicine, baptized in the discovery of REM sleep in 1953 and by the characterization of sleep cycles a few years later, initially focused on adult physiology and sleep disorders.
Only in the past 2 decades has the study of children produced a substantial, if sometimes controversial, body of knowledge concerning sleep and its effects on development. Although many findings have been perplexing, the relevance of sleep pathology for behavioral and mental development has been securely established, and some of the most interesting research developments concern the role of sleep in ADHD.
Sleep, cognition, and behavior
Serious sleep problems usually imply either too much or too little sleep. Too little sleep can mean abbreviated sleep episodes, as might be imposed by external demands or by insomnia, or longer episodes punctuated by arousals that fragment sleep. Pilcher and Huffcutt1 examined the effects of prolonged sleep deprivation (more than 45 hours), brief sleep deprivation (45 hours or less), or partial sleep deprivation (less than 5 hours of sleep in a 24-hour period) on measures of cognitive and motor performance or mood. The overall performance decrement for all measures was 1.37 standard deviations (SDs). This is comparable to a drop in IQ from 100 to about 80. Under the conditions of partial sleep deprivation—not unlike a typical Monday morning for many of us—mood scores dropped by over 4 SDs.
Although children are not suitable subjects for such experiments, Sadeh and colleagues2 demonstrated that very modest changes in sleep duration can substantially affect the neurobehavioral function of children. His team monitored 77 fourth and sixth graders in regular classrooms with actigraphy for 5 nights. For the first 2 nights, children slept as usual; on the remaining 3 nights, they were asked to either extend or restrict their sleep time by 1 hour. Children who failed to change their sleep duration by at least 30 minutes were analyzed as “no change.” On a simple reaction time test, performance of both the sleep restriction and no-change groups deteriorated, whereas on measures of digit span and continuous reaction time, children in the extended-sleep group performed significantly better than the others.
When Gruber and associates3 applied a single hour’s sleep restriction to 11 children with ADHD and to 32 controls over 6 days, neurobehavioral function in both groups deteriorated, as assessed by a continuous performance test. For children with ADHD, two-thirds of the continuous performance test measures dropped from the subclinical to the clinical range of impairment.
If the slight manipulations in sleep duration have measurable effects after just 3 nights, what might the effects be when sleep is shortened or fragmented long-term by busy family schedules, sleep-related breathing disorders (SRBD), behavioral insomnia of childhood, or other sleep problems? Would it be possible to produce the full clinical picture of ADHD under such circumstances?
correlation between ADHD and sleep disorders in children?
? ADHD has been linked to many types of sleep problems in numerous and methodologically diverse studies. Parent-reported sleep complaints may occur in as many as 50% of children with ADHD.
? This article reviews current thinking on the association between ADHD and sleep disorders that is especially relevant to practicing psychiatrists.
? Children presenting with ADHD or ADHD symptoms frequently have sleep problems that parents can describe on a questionnaire or in an interview. Sleep disturbances may aggravate an underlying psychiatric disorder or even fully account for the psychiatric presentation; such information may be critical in diagnosis, referral, and treatment planning.
Prevalence of sleep disorders
Sleep problems described in children with ADHD include behavioral problems that often manifest as resistance to bedtime or difficulty in going back to sleep in the middle of the night without caregiver presence, parasomnias, sleep-disordered breathing, restless legs and periodic leg movements, and circadian rhythm disorders.4 Similarly, children with ADHD experience alterations in sleep architecture, such as delayed onset of REM, reduced time in REM, and arousals with sleep fragmentation.5 Inattention, hyperactivity, neuropsychological deficits, syndromic ADHD, and behavior disorders are also common among children who present with sleep problems. Yet despite abundant evidence of these comorbidities, the extent and nature of possible causal relationships between disturbances in sleep and behavior remain largely a mystery.
Prevalence estimates vary because of the way sleep disorders are operationally defined. Subjective parent complaints about resistance to bedtime, a behavior that is not unusual in children, may be counted as a significant problem or disorder by one investigator but not by another. Laboratories may use different procedures or scoring schemes that produce somewhat inconsistent counts of polysomnographic events, such as leg movements and hypopneas. Similarly, heterogeneous diagnostic rules may yield disparate rates of disorder, ie, if 5 rather than 1 apnea or hypopnea episodes per hour define obstructive sleep apnea, fewer cases with more severe symptoms on average will result. Finally, deviations in sleep architecture detected on polysomnography may be consequential yet may not be indicative of a specific sleep diagnosis. Similarly, diagnoses of ADHD depend on the criteria set, subjective thresholds for counting a behavior as symptomatic, and whether diagnoses are based on rating scales, clinical interviews, or structured and comprehensive clinical assessments.
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