Bipolar disorder and delayed sleep-wake phase disorder: Findings on sustained attention, sleep, and circadian rhythm parameters

Abstract

BackgroundSleep and circadian rhythm disruptions can contribute to cognitive disturbances in bipolar disorder (BD); however, the profile of specific sleep/circadian phenotypes remains to be elucidated. The aim of our work is to compare sleep/circadian parameters and sustained attention between patients with BD and comorbid delayed sleep-wake phase disorder (BD-DSWPD), patients with BD without DSWPD comorbidity (BD-Control), and healthy controls (HC). MethodsBD patients (N = 70, BD-DWSPD N = 25, BD-Control N = 45) and HC (N = 86) were evaluated through actigraphy for sleep and circadian rhythm parameters, the Pittsburgh Sleep Quality Index for sleep quality, the reduced Morningness-Eveningness Questionnaire for chronotype and the Psychomotor Vigilance Task for sustained attention. ResultsThe BD-DSWPD diagnosis was associated with poorer self-reported sleep quality, lower sleep efficiency, higher wake after sleep onset, and later acrophase compared to both HC and BD-Control groups. BD-DSWPD was also associated with lower relative amplitude compared to HC. Regarding sustained attention variables, the diagnosis of BD-DSWPD was associated with increased response times compared to HC, while both BD-DSWPD and BD-Control were associated with major lapses than HC. LimitationsSample size and multivariate statistics not adjusted for pharmacological treatment. ConclusionsPatients with BD-DSWPD showed greater disturbances in sleep and circadian rhythm parameters compared to both HC and BD-Controls; moreover, BD-DSWPD showed increased response times compared to HC. Further studies are required to evaluate whether treatments focused on advancing the sleep phase may contribute to improving cognition, sleep, and circadian rhythmicity in patients with BD and comorbid DSWPD.