297 The Relationship Between Sleep and Objectively Measured Sedentary Behavior in Adults with Desk Jobs

Abstract

Abstract Introduction Both poor sleep and sedentary behavior lead to negative health outcomes. While some previous studies have observed an association between poor sleep and greater sedentary behavior, few studies have assessed this relationship using an objective measure of sedentary behavior. We examined the association of both self-reported and objectively-measured sleep with objectively-measured sedentary behavior. Methods In a secondary analysis of baseline data from an ongoing clinical trial, the present analysis included 157 physically inactive adults with elevated blood pressure (120–159 mmHg systolic or 90–99 diastolic) and desk jobs (82.8% white, 65.6% female, age 45.5±12.0). To assess sedentary behavior, participants wore an accelerometer/inclinometer (activPAL3 micro) on the upper thigh continuously for 7 days. Variables included total sedentary time, prolonged sedentary time (≥30 minute bouts), and sit-to-stand transitions; these were averaged across all waking hours as well as the workday. To assess sleep, participants completed the Pittsburgh Sleep Quality Index (PSQI) and a subsample (n=57) wore an Actiwatch Spectrum for 7 nights. Variables examined included the PSQI global score, actigraphy-based total sleep time (TST) and sleep efficiency (SE). Linear regression examined associations between sleep and sedentary behavior, with adjustments for age, gender, race, body mass index, and activPAL3 wear time. Results Participants had (mean±standard deviation) 11.1±1.5 hours sedentary time per day, with 6.3±2.0 occurring in ≥30 minute bouts, and 51.3±13.4 sit-to-stand transitions. During the workday, participants had 6.6±1.3 hours sedentary time with 3.8±1.7 occurring in ≥30 minute bouts and 27.2±11.2 sit-to-stand transitions. PSQI global score was 4.9±2.9; 32.5% were classified as poor sleepers. Actigraphic TST was 6.7±0.8 hours, with SE of 85.4±6.3%.Greater SE was associated with less sit-to-stand transitions during the workday (β=-0.36, p=0.01) and during the full day (β=-0.37, p=0.01). Subjective sleep quality and actigraphic TST were not associated with sedentary behavior. Conclusion We did not find a cross-sectional association between sedentary behavior and sleep in insufficiently active adults, potentially due to restricted range of sedentary behavior and physical activity in the sample. The association between greater sleep efficiency with fewer sit-to-stand transitions is counterintuitive and warrants further exploration. Support (if any) This study was funded by National Institutes of Health (NIH) grants R01HL134809 and R01HL147610.