ObjectivesDelayed sleep-wake phase disorder (DSWPD) most commonly affects young individuals (adolescents and young adults), but it is often undetected in clinical practice. Despite several reports suggesting a link between DSWPD and depression, no systematic review has investigated this association. The aim of this systematic review was to determine whether DSWPD is associated with depression among young individuals.MethodsMEDLINE, EMBASE, PsycINFO, and CINAHL Plus were searched up to 29 July 2024. Primary studies investigating DSWPD and depression among young individuals were eligible. Methodological quality and risk of bias was assessed with the National Institute of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Common-effect models were conducted to examine the relationship between DSWPD status (categorical variable: yes or no) and depression severity (continuous variable). PROSPERO ID: CRD42023458889.ResultsSixteen studies were included with 766 participants being evaluated against the diagnostic criteria for DSWPD from the International Classification of Sleep Disorders. Thirteen out of 15 studies demonstrated that young individuals with DSWPD had a significantly greater severity of depressive symptoms than young individuals without DSWPD. NIH quality assessment scores ranged between 5 and 9 (out of a total of 11). DSWPD status had a significantly large effect on depression severity in the common-effect model (: 16 estimates, 693 participants, Cohen's= 0.92, 95% confidence interval (95% CI) [0.76-1.08]). The subgroup analysis also demonstrated significant findings with the common-effect model that only utilized data from studies that controlled for psychiatric disorders (: 12 estimates, 535 participants, Cohen's= 0.88, 95% CI [0.70-1.06]).ConclusionsDSWPD is associated with a greater severity of depressive symptoms among young individuals. Although more research is required to understand this association, it may be useful to consider the presence of DSWPD when managing young individuals who present with persistent sleep disturbances (e.g., sleep-onset insomnia) and depressive symptoms. N d N d
