P022 Can breaking up sitting during dayshifts and nightshifts improve sleep?

Introduction Inadequate sleep and sedentary behaviour are common for shiftworkers and contribute to poor health. Interventions that promote physical activity and reduce sedentary behaviour could be beneficial for improving sleep in shiftworkers. The current study investigated the effects of breaking up sitting with physical activity during dayshifts and nightshifts on sleep architecture during a 9h or 5h sleep. Method Participants (n = 125, 51% male, 23.4 ± 4.8y) completed an in-laboratory sleep study with five simulated day or nightshifts. During shifts, participants in the breaking up sitting (BUS) conditions completed a 3min walk on a treadmill every 30mins. Sleep opportunities were either 9h or 5h. Participants were allocated to one of six conditions: 1) Sedentary (SED), dayshift, 9h sleep; 2) BUS, dayshift, 9h sleep; 3) SED, dayshift, 5h sleep; 4) BUS, dayshift, 5h sleep; 5) SED, nightshift, 9h sleep; 6) BUS, nightshift, 9h sleep. Polysomnography was used to measure sleep outcomes. Results For dayshifts, mixed model ANOVAs demonstrated significant interactions between condition and experimental day, whereby those in the 9h sleep conditions had longer total sleep time (p<.001), shorter sleep onset latency (p<.001), and more slow-wave sleep (N2 and N3; p=.03) during sleep opportunities 1-4. There were no significant differences in sleep between the nightshift physical activity conditions. Conclusion Better sleep quality was seen in the 9h condition, with no effect of breaking up sitting. Given the benefits of breaking up sitting on health, our findings suggest that breaking up sitting interventions can be promoted without detrimental impacts on sleep.