Background: Flexible work arrangements (FWA) allow for work demands to extend into non-work hours, challenging employees' detachment from work. The extent of detachment may influence sleep and physical activity. However, organizational initiatives to influence detachment, and thus likely the 24-hour compositions of physical behaviors, among workers with FWA are sparse.

Aim: To examine the effects of a workplace intervention on the 24-hour composition of physical behaviors among office workers with flexible work.

Methods: The intervention introduced work strategies to promote detachment through an individual-level course on how to use digital tools and a workgroup-level workshop to develop common rules and routines in flexible work. Accelerometer and diary data were collected at baseline in an intervention group (eventually received both intervention activities, n=27) and a control group (no intervention, n=21), and again at a 12-month follow-up after the intervention to document sleep, physical activity, and inactivity.  Using compositional data analysis, we calculated two log-transformed ratios (ILR): 1) sleep relative to time awake and 2) physical activity relative to inactivity within time awake. Intervention effects were analyzed using Repeated Measures ANOVA.

Results: In the intervention group, sleep increased from 26% at baseline to 29% at follow-up, while time being active remained at 6% and inactivity decreased from 68% to 65%. In the control group, sleep decreased from 29% to 27%, time being active increased from 5% to 6%, and inactivity increased from 66% to 67%. Intervention effects on sleep were significant, while no significant difference in physical activity was observed between the groups.

Conclusions: The intervention was effective in increasing sleep in the intervention group compared to the control group but did not affect physical activity relative to inactivity. Employers may thus facilitate sleep in workers with FWA by implementing strategies promoting detachment at individual and workgroup levels.