Sleep duration and mental health in young adults

The association between sleep duration and mental illness has been established in middle-aged and older populations, yet remains less explored in younger adults. Additionally, a common limitation to existing studies is the lack of statistical power to explore less common disorders. The purpose of this study was to examine sleep duration as a predictor for a range of mental disorders and well-being in a longitudinal sample of young adults. Data were derived from two waves (w1, w2) of the SHoT survey, which invited all full-time university and college students in Norway. The response rates were 34.4 % (n = 62,498) in 2021 (w1) and 35.1 % (n = 59,554) 2022 (w2). This study utilized a nested longitudinal sample from both w1 and w2, encompassing 21,289 students. Demographics, sleep duration (w1), and mental health (w2) were measured by self-report questionnaires. Sex-stratified linear regression models and log-link binomial regression analyses were employed to determine the proportion and calculate the risk ratios, respectively, for mental illness across different sleep duration categories. The mean age of the sample was 24.8 years ± 4.5 years (w1). Students with shorter sleep durations, and to some degree longer sleep durations (illustrating a ᒐ-shaped association), exhibited a higher risk for all assessed mental disorders and well-being outcomes one year later, compared to students sleeping 8–9 h. The ᒐ-shaped trend was consistent for both female and male students. Sleep duration appears to be a transdiagnostic marker for mental health in young adults.