A 2-year follow-up study on the course of at-risk delayed sleep-wake phase disorder in the young generation and its...

This study investigated the course of at-risk Delayed Sleep-Wake Phase Disorder (DSWPD) in the young general population through follow-up surveys conducted at 2-year intervals. In 2019, 7,810 individuals responded to a web-based questionnaire, and in 2021, 2,375 participants completed the same survey, of whom 1,370 met the inclusion criteria. The survey assessed demographic variables, sleep habits, and daytime functioning, including the number of absent days in the preceding month. It also measures scores from the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) for evaluating DSWPD status, the Work Limitation Questionnaire, the SF-8, and the Kessler Psychological Distress Scale (K6). Individuals were considered at risk for DSWPD if they had a BRIAN score of 40 or higher and four or more days absent per month. At follow-up, 1.9 % of the population was at risk for DSWPD, with 14.5 % of those initially at risk remaining, representing 0.5 % of the total study population. The persistently at-risk group had higher absenteeism, while the newly onset group experienced similar work productivity and quality of life declines. Additionally, although the improved group reduced absenteeism to a level below the cutoff at follow-up, their sleep-wake schedule remained delayed, their BRIAN score was higher, and their K6 and productivity loss scores were worse than those of the persistently normal group. The findings emphasize the importance of early intervention for individuals with newly developed DSWPD and careful monitoring of those who have improved from DSWPD.