Children with attention-deficit/hyperactivity disorder (ADHD) have high rates of sleep problems and sleep disorders. It is critical that pediatricians assess for sleep problems during the course of ADHD assessment and when treating children with stimulant medication. Sleep must be considered in the differential diagnosis and in terms of comorbidity with ADHD. The most common sleep problem in children with ADHD is insomnia, and the first line of treatment should be the implementation of behavioral interventions rather than medication. More research is needed to determine if children with ADHD respond to behavioral interventions in a similar manner as typically developing children.
There are several published guidelines describing the assessment and treatment of attention-deficit/hyperactivity disorder (ADHD), including practice parameters developed by the American Academy of Pediatrics (AAP), the American Academy of Child and Adolescent Psychiatry (AACAP), the Canadian Attention Deficit Hyperactivity Disorder Resource Alliance (CADDRA), and the National Institute for Health and Clinical Excellence (NICE). Recent research has indicated that primary care clinicians are aware of these guidelines and generally follow the clinical practice recommendations provided. However, while available ADHD practice parameters are fairly comprehensive, it is notable that the important role of sleep in the assessment and treatment of ADHD is either not mentioned at all (eg, AAP) or receives little focus. Therefore, the goal of this review is to provide pediatricians involved in the assessment and treatment of ADHD in school-aged children with a framework for evaluating and managing sleep-related concerns in the clinical setting.
Attention-deficit/hyperactivity disorder
ADHD is the most common childhood mental health disorder, affecting approximately 5% of school-aged children worldwide. Children are typically diagnosed with ADHD during the elementary school years, with boys being diagnosed more often than girls (sex ratio ranges from 3:1 to 8:1). ADHD is often chronic in nature with symptoms persisting into adolescence and adulthood in approximately two-thirds of children. Children with ADHD typically display a heterogeneous combination of disruptive behavior, academic underachievement, and difficulty with social and familial relations, as well as high rates of comorbidity with other clinical disorders. In fact, research has found that the vast majority (up to 87%) of children with ADHD meet criteria for one other mental health disorder and approximately half of all children diagnosed with ADHD have 2 or more comorbid disorders, with the most common being disruptive behavior disorders (ie, oppositional defiant disorder and conduct disorder), anxiety and mood disorders, and learning disabilities.
ADHD is conceptualized as a neurobiological disorder in which the primary cause is thought to result from a complex set of genetic factors, although nongenetic factors (eg, perinatal stress, prematurity, traumatic brain injury, maternal substance abuse during pregnancy) have also been postulated to play a role in the etiology of this disorder. These genetic and nongenetic factors are thought to influence brain structure (ie, the integrity of the prefrontal cortical-striatal network) and function (ie, neurotransmitter systems such as the catecholamine system), and ultimately affect behavior. In terms of theoretical models, the cognitive-energetic model is one that provides a particularly comprehensive framework for understanding the neurocognitive deficits associated with ADHD. This model indicates that problems associated with ADHD occur at 3 levels: (1) cognitive mechanisms (eg, response outputs such as motor organization), (2) energetic pools (eg, arousal, activation, and effort), and (3) executive functioning (eg, inhibition, working memory, planning). It is assumed that these problems are related to differences in the underlying neural architecture and modulator systems in individuals with ADHD.
ADHD increases the risk for numerous adverse health outcomes later in development, including substance abuse, motor vehicle accidents, and involvement with the justice system. As such, ADHD represents a significant burden to individuals, their families, and society. Given the heterogeneity of the disorder in its 3 recognized subtypes (namely Predominately Inattentive, Predominately Hyperactive-Impulsive, Combined), and its pervasive impact on children, it is often recommended that treatment involve multiple modalities, including behavioral, psychoeducational, and pharmacological interventions. Long-term prospective studies, however, such as the Multimodal Treatment Study of Children with ADHD (MTA), have suggested that an optimal level of pharmacological medication is the single most effective treatment for ADHD in most children, at least for the first year of treatment. Moreover, stimulant medication alone remains the most common treatment for ADHD.
ADHD and Sleep
ADHD has one of the highest rates of sleep problems of all child mental health disorders. There have been numerous systematic reviews of the literature on the sleep characteristics of children with ADHD, as well as articles written about this relationship for clinical audiences. All reviews concur that parents of children with ADHD report more sleep problems than do parents of typically developing children. Prevalence estimates of sleep problems based on parent reporting have varied widely, but have been consistently high (ie, 50%–80%), depending on the operational definition of sleep problem used. The sleep problems most commonly reported by parents of children with ADHD are difficulties initiating or maintaining sleep, both of which typically shorten sleep duration and can cause problems for the family and child. Although sleep problems are common in children with ADHD, these are often overlooked and rarely included in research examining the comorbidity of ADHD. For example, the largest treatment trial of ADHD, the MTA study, examined comorbidities associated with ADHD but did not include sleep disorders.
Sleep problems have also been shown to be related to ADHD subtype. Most research has indicated that children with the Combined subtype of ADHD have more sleep problems compared with children with the Inattentive or Hyperactive/Impulsive subtypes of ADHD. However, there is also some evidence that children with the Inattentive subtype of ADHD may be sleepier during the day than their typically developing peers, despite their nocturnal sleep being similar. A recent study also found that hypersomnia was more prevalent in the Inattentive subtype, whereas circadian rhythm problems were more prevalent in the Combined subtype. When interpreting these results, it is important to consider the potential confound of ADHD symptom severity across the subtypes and the possible impact of this on research findings.
The high rates of sleep problems reported by parents of children with ADHD are not often verified by research using objective measures of sleep (eg, actigraphy and polysomnography [PSG]). Although several individual research studies have found a higher rate of a specific sleep disorders (eg, sleep apnea) or a specific sleep architecture variation (eg, differences in rapid eye movement [REM] sleep), a meta-analysis by Sadeh and colleagues found that the only consistent finding across studies was a higher rate of periodic limb movement disorder (PLMD) in children with ADHD when compared with typically developing children. All other sleep disorders (eg, sleep apnea) and differences in sleep architecture were associated with ADHD through mediating factors including age, gender, and comorbidity. This finding is in contrast to results of the meta-analysis by Cortese and colleagues of PSG studies, which found that children with ADHD had higher scores on the index indicating sleep apnea. Unfortunately, periodic limb movements were not included in the analyses. The investigators of both of these meta-analyses highlight that there is wide variability across studies in terms of definitions and measurement of these sleep disorders, and that this variability may result in inconsistent findings across studies.
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