Coherency of attention deficit/hyperactivity and sleep-related problems
Results from a cross-sectional study in elementary school children
Original ContributionChildren with ADHD exhibit more sleep problems than normal children with estimations between 25-50% [7] compared with 11-37% in elementary school children [29,37]. However, reports from polysomnografic studies did not reveal a characteristic sleep feature or architecture for AD-HD children apart from REM sleep alterations [6]. For a review of the literature see Sadeh et al. [33]. Sleep problems in ADHD may be due to oppositional defiant disorder or secondary to stimulant medication [8,9,24,33],Recently several studies discuss a possible relationship between sleep problems in ADHD children and adolescents and increased daytime sleepiness and vigilance problems as a result of difficulties in arousal regulation [10,14]. In a population-based survey of Chinese adolescents, a highly significant and negative association between sleep duration and ADHD symptoms could be identified [22]. A further epidemiological study [36] also reported a significant association between dyssomnia and ADHD-related symptoms.Differential diagnostic considerations highlight that sleep disorders such as restless legs syndrome (RLS) and sleep-disordered breathing (SDB) and especially obstructive sleep apnea (OSA) may lead to impaired daytime functioning, in particular hyperactivity and attention deficits [2,16,17]. In a population-based cross-sectional survey the presence of SDB symptoms was associated with an approximately 2-fold increase in the prevalence of hyperactivity and inattention [15]. Chervin et al.[4] reported a higher extent of hyperactivity in 22% of children with habitual snoring in contrast to only 12% of non-snoring children with an odds ratio for elevated hyperactivity of 2.2 after adjustment for age and gender.Apart from SDB, RLS, and periodic limb movement disorder (PLMD) have also been reported to be related to 31,32,33]. Picchietti et al. [31] demonstrated a RLS frequency of 12% in a group of 69 children with ADHD. A lower prevalence of 7.1% was observed by Kirk and Bohn [20]. The highest prevalence of RLS/PLMS seems to occur in combination with SDB. An approximate estimate of RLS in children without comorbidity is much lower (1.3%; [19]).The Cologne Sleep Study was aimed at providing information on sleep problems in school-aged children. The children were surveyed annually for three subsequent years. To our knowledge, only few comparable surveys exist assessing the relationship between various sleep problems and ADHD on a broad basis.We followed the question whether an increased risk for hyperactivity or ADHD symptoms exists in the presence of sleep onset problems or sleep maintenance problems and impaired daytime vigilance.First, we hypothesized that the presence of these sleep problems may be related to an increased risk for hyperactivity.Second, we postulated a significant relationship between impaired daytime vigilance and hyperactivity symptoms.Third, we ass...