People with attention-deficit/hyperactivity disorder (ADHD) experience higher rates of sleep difficulties coupled with greater circadian preference for eveningness. Emerging evidence suggests that symptoms of cognitive disengagement syndrome (CDS) may be associated with sleep difficulties and eveningness preference independently of ADHD symptoms. However, most studies have been conducted with children, adolescents, or college students. This study examined unique associations between ADHD and CDS symptom dimensions and sleep problems and circadian preference in a non-referred sample of adults. 106 adults (ages 18-75 years; Mage = 38.69 years) completed self-report assessments of ADHD and CDS symptoms, sleep quality and functioning, and circadian preference. ADHD inattentive (ADHD-IN), ADHD hyperactive-impulsive (ADHD-HI), and CDS symptoms evinced differential unique associations in regression analyses. Only ADHD-IN symptoms were uniquely associated with more frequent sleep medication use. Only ADHD-HI symptoms were uniquely associated with shorter sleep duration and greater nighttime sleep disturbance. Only CDS symptoms were uniquely associated with poorer sleep quality, longer sleep onset latency, greater daytime dysfunction, greater global sleep impairment, and greater eveningness preference. Findings support the importance of considering the role of CDS in sleep disturbance and circadian preference in adults with ADHD and point to the need for careful assessment of these dimensions in research and clinical care.
