Daily Timing Of Device-assessed Moderate To Vigorous Physical Activity And Sleep Quality

PURPOSE: The benefits of daily moderate to vigorous physical activity (MVPA) for sleep quality in pregnancy may vary based on time of day. The goal of this study is to examine the associations of timing of daily MVPA with measures of sleep quality across pregnancy. METHODS: Data (N = 928 days) come from a feasibility study of 9 participants at Kaiser Permanente Northern California enrolled in their first trimester and followed up to 35 weeks' gestation. Participants wore Actigraph’s Centrepoint Insight Watch accelerometer day and night. The Hibbing TwoRegressions algorithm assigned MET values to each minute of wear time and the Tracy algorithm classified minutes of bedrest (a proxy for sleep), respectively. The waking time window that had ≥50% of the day’s MVPA was considered dominant. Categories for MVPA timing: morning-dominant = 0500-1100, mid-day-dominant = 1100-1700, evening -dominant = 1700-0000, mixed, and no MVPA. Mixed effects models estimated daily associations of classification of MVPA timing (evening-dominant reference) with bedrest duration and efficiency (i.e., number of bedrest minutes during the overnight bedrest period by the number of total minutes in the bedrest period, specific to that night, x100%). Models adjusted for daily device wear-minutes and total MVPA volume. RESULTS: Most days were classified as either evening (63%) or afternoon (28%) dominant. On average, bedrest duration lasted 8.6 (SD 2.1) hours with 94% bedrest efficiency. Compared to evening-dominant, mid-day-dominant and mixed MVPA was associated with 0.4 [95% Confidence Interval (CI) = 0.12, 0.67] and 0.92 (CI = 0.37, 1.47) hours longer sleep duration, respectively. Conversely, morning-dominant MVPA was associated with 2.1 hours shorter sleep duration (CI = -3.14, -1.05), and 8.93% lower sleep efficiency (CI = -14.75, -3.11) compared to evening-dominant. CONCLUSIONS: Engaging in MVPA during the afternoon or spread throughout the day, may be more advantageous than in the morning or evening for pregnant people who want to increase their duration and efficiency of sleep.