The effect of replacing prolonged sitting with intermittent standing during a simulated workday on the subsequent night's sleep.

A bout of leisure-time physical activity improves sleep on the subsequent night. However, whether breaking up sedentary time during the workday improves sleep is unknown. The purpose of this study was to examine whether breaking up prolonged sitting by standing during the workday leads to better sleep the following night. 25 inactive adults (16 males, 42.4 ± 11.8 years, body mass index: 31.9 ± 5.0 kg/m) participated in a randomized crossover trial consisting of two simulated 8-h workdays involving prolonged sitting (SIT) or alternating sitting and standing every 30 min (SIT-STAND). Sleep was assessed on the night following each workday. Participants completed a diary and wore a wrist accelerometer (Actiwatch Spectrum) to assess multiple dimensions of sleep (e.g., timing, duration, wakefulness, quality). Paired -tests and Hedges' effect sizes evaluated differences in sleep across conditions. Self-reported wakefulness after sleep onset (WASO) was significantly lower following SIT-STAND compared to SIT (13.9 ± 30.1 min vs. 23.2 ± 38.6 min;  = 0.03,  = - 0.51), mirrored by a small-sized nonsignificant reduction in accelerometer-assessed WASO following SIT-STAND compared to SIT (32.7 ± 13.6 min vs. 40.8 ± 25.8 min;  = 0.06,  = - 0.38). Mean accelerometer-based activity levels during sleep were also lower following SIT-STAND compared to SIT (10.8 ± 14.5 vs. 14.7 ± 10.4 counts/min;  = 0.03,  = - 0.47). Other sleep outcomes (e.g., bed- and wake-time, total sleep time, sleep onset latency) were not different between conditions. Alternating sitting and standing rather than prolonged sitting during a simulated workday modestly reduces night-time wakefulness. Whether similar benefits occur with long-term reduction in workplace sedentary behavior deserves further exploration.