Evening chronotype is overrepresented in adults with attention-deficit/hyperactivity disorder (ADHD), yet how circadian preference relates to specific symptom dimensions remains unclear. Cognitive Disengagement Syndrome (CDS; formerly Sluggish Cognitive Tempo), characterized by daydreaming, mental fogginess, and hypoarousal, is considered distinct from ADHD despite overlap and may be relevant to associations among chronotype, sleep, and attentional symptoms. This cross-sectional study tested an a priori serial mediation model in 100 treatment-seeking adults with attentional complaints and no prior ADHD diagnosis or pharmacotherapy. Participants completed the Morningness-Eveningness Questionnaire, Pittsburgh Sleep Quality Index, Barkley Adult Sluggish Cognitive Tempo Rating Scale, and Adult ADHD Self-Report Scale (ASRS-v1.1). Eveningness was associated with poorer sleep quality, and poorer sleep quality with higher CDS symptoms. CDS was strongly associated with both inattention and hyperactivity/impulsivity. The serial indirect effects through sleep quality and CDS were significant for both dimensions, whereas simple indirect effects were not. The full models explained 50.0% and 21.3% of the variance in inattention and hyperactivity/impulsivity, respectively. Supplementary analyses localized this effect to the Daydreaming rather than Sluggishness subdimension. Findings were robust to age- and sex-adjustment. These findings suggest sleep quality and CDS are clinically relevant correlates of ADHD symptom dimensions, though longitudinal confirmation is needed.
Circadian Biology