Delayed Circadian Rhythm in Adults with Attention-Deficit/Hyperactivity Disorder and Chronic Sleep-Onset Insomnia

Background: Previous studies suggest circadian rhythm disturbances in children with attention-deficit/hyperactivity disorder (ADHD) and sleep-onset insomnia (SOI). We investigate here sleep and rhythms in activity and melatonin in adults with ADHD. Methods: Sleep logs and actigraphy data were collected during 1 week in 40 adults with ADHD, of whom 31 reported SOI. Salivary melatonin levels were assessed during 1 night. Sleep measures, circadian activity variables, and dim light melatonin onset were compared between groups of ADHD adults with and without SOI and with matched healthy control subjects. Results: Compared with control subjects, both groups of ADHD adults had longer sleep-onset latency and lower sleep efficiency. Adults with ADHD and SOI showed a delayed start and end of their sleep period and a delayed melatonin onset compared with adults with ADHD without SOI (p = .006; p = .023; p = .02) and compared with healthy control subjects (p = .014; p = .019; p = .000). Adults with ADHD and SOI also showed an attenuated 24-hour amplitude in their rest-activity pattern, in contrast to those without SOI, who showed a higher day-to-day stability. Conclusions: These findings demonstrate diurnal rhythm deviations during everyday life in the majority of adults with ADHD that have SOI and suggest that potential benefits of rhythm-improving measures should be evaluated.