Physical exercise, Sedentary Behaviour, Sleep and Depression Symptoms in Chinese Young Adults During the COVID-19 Pandemic: A Compositional Isotemporal Analysis

Numerous studies links movement activity (e.g., physical activity, sedentary behavior [SB], and sleep) with mental health or illness indicators during the COVID-19 pandemic; however, research has typically examined time-use behaviors independently, rather than considering daily activity as a 24-hour time-use composition. This cross-sec-tional study aimed to use compositional isotemporal analysis to estimate the association between reallocation of time-use behaviors and depression symptoms in young adults in China. Participants (n = 1475; 68.0% of female; 20.7 [1.60] years) reported their time spent in moderate to vigorous physical activity (MVPA), light physical activity (LPA), SB, and sleep. Replacing SB with sleep, LPA, and MVPA at 5, 10, or 15 min was significantly associated with lower estimated depression symptoms scores. For example, adding MVPA from SB at 15 min was associated with lower depression symptoms scores (estimated difference: −0.13 [−0.17, −0.09]). The associations between reallocation of time use behaviors with depression symptoms scores were slightly differentiated. Our results emphasize the importance of increased MVPA and decreased SB as well as their mutual replacements for lowering the risks of depression symptoms in young adults during the COVID-19 pandemic. Our results can inform policy to develop effective plans and strategies for mental health promotion.