Adult attention-deficit hyperactivity disorder and clinical correlates of delayed sleep phase disorder

•Delayed sleep phase disorder is highly prevalent in adults with ADHD•ADHD patients with DSPD are younger with a greater cannabis use compared to ADHD patients without DSPD•Delayed sleep phase disorder is correlated with higher affective temperamental traits and emotional dysregulation in adults with ADHD•Delayed sleep phase disorder increases the global impairment in ADHD subjects The purpose of the study was to assess the prevalence and clinical correlates of Delayed Sleep Phase Disorder (DSPD) in adults with Attention-Deficit/Hyperactivity Disorder. Participants were 102 adults (Female= 27), aged 18-65 (mean age= 28.2 years), with ADHD diagnosed in adulthood. ADHD and DSPD diagnosis were made according to DSM-5 criteria. Assessing instruments included the Morningness-Eveningness Questionnaire, the brief Temperament Evaluation of Memphis, Pisa, Paris and San Diego Questionnaire, the Barratt Impulsiveness Scale, the Reactivity Intensity Polarity Stability Questionnaire-40 and the World Health Organization Disability Assessment Schedule 2.0. Epidemiological and Clinical features were compared in patients with and without DSPD. 34 out of 102 patients were classified as having a Delayed Sleep Phase Disorder. As expected, DSPD patients reported a more frequent evening chronotype. In the multivariate logistic regression analysis, Delayed Sleep Phase Disorder was significantly associated with young age, cannabis use, cyclothymic temperamental traits and severe global impairment. An early diagnosis with a proper treatment targeted to both disorders may be fundamental in order to improve the overall functioning and the outcome of adult ADHD patients.