Chronotype and sleep disturbances: A comparative analysis of sluggish cognitive tempo and attention deficit hyperactivity disorder

Recent investigations into Sluggish Cognitive Tempo (SCT), also known as Cognitive Disengagement Syndrome, have primarily focused on its association with ADHD. However, emerging evidence suggests SCT may be a distinct clinical entity, despite frequent co-occurrence with ADHD symptomatology. While ADHD studies have elucidated sleep patterns and chronotype preferences, SCT research has largely focused on ADHD-comorbid cases, providing limited data on community-based adolescents and adults. This study aims to investigate sleep disturbances and chronotype characteristics in individuals with pure SCT compared to those with ADHD and healthy controls within a clinical sample. We utilized the DSM-IV-based Disruptive Behavior Disorders Rating Scale (DBDRS-parent and teacher form), Barkley Sluggish Cognitive Tempo Scale (BSCTS), the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS), Children's Sleep Habit Questionnaire, and Children's Chronotype Questionnaire for the evaluation of children with SCT, ADHD, and healthy controls. Our findings revealed shorter sleep duration in ADHD (n: 67) children compared to both SCT (n: 50) and healthy controls (n: 50), with no significant difference between SCT and healthy controls (<i>p</i> < 0.001). Eveningness tendencies were highest in SCT but also elevated in ADHD compared to controls (<i>p</i> < 0.001). Additionally, daytime sleepiness was highest in SCT and higher in ADHD than controls (<i>p</i> < 0.001). Regression analyses demonstrated that SCT severity predicted both daytime sleepiness and eveningness.