Links Between Early And Late Day MVPA And Sleep During A Sleep Extension Intervention

PURPOSE: Determine if timing of physical activity is associated with sleep duration, staging, and quality in people with habitual short sleep completing a sleep extension intervention. METHODS: 10 adults (age = 20.6 ± 2.3 years; BMI = 22.5 ± 2.4 kg/m2; 50% Female) with self-reported short sleep duration (<6.5 hrs/night), were recruited for a 4-week at-home sleep extension intervention, where participants were coached to extend their time in bed by 2 hours/night. At baseline and during week 4 of sleep extension, free-living moderate-to-vigorous physical activity (MVPA; ≥3 METS) was evaluated via accelerometry. Additionally, total sleep time (TST), staging (rapid eye movement [REM], and non-REM stages 1, 2, and 3), and quality (sleep onset latency [SOL], wake after sleep onset [WASO], and sleep efficiency [SE]) were evaluated via electroencephalography. During sleep extension, participants were classified as early day MVPA (E-MVPA) or later day MVPA (L-MVPA) based on if they accumulated the majority (>50%) of their MVPA before or after, respectively, the sample median time of 15:10. Linear mixed-models analyzed differences between MVPA groups and sleep outcomes. RESULTS: For all participants at baseline, TST was 5.42 ± 1.32 hrs and daily MVPA was 45.2 ± 24.4 min, with no significant differences between MVPA timing groups. Daily MVPA during sleep extension did not differ between E-MVPA and L-MVPA (34.3 ± 2.9 vs. 44.6 ± 6.1 min, respectively). TST and REM sleep increased more in L-MVPA compared to E-MVPA (TST: 108.2 ± 84.6 vs 37.8 ± 92 min, p = 0.002; REM: 40.0 ± 44.5 vs. 4.3 ± 30 min; p = 0.003) during sleep extension. No significant differences between groups were observed for non-REM sleep stages, SOL, WASO, or SE. CONCLUSIONS: Our preliminary findings show participants with late afternoon and evening accumulation of MVPA had greater improvements in TST and REM sleep during the sleep extension intervention, without detrimentally altering other aspects of sleep physiology. Given the association between poor sleep and cardiometabolic disease, later-day MVPA may help reduce disease risk by improving sleep, especially in people with habitual short sleep duration. Larger fully powered randomized controlled trials are needed to confirm our findings in higher risk populations. Supported by: NIH-UL1TR002538; NIH-K01HL145099; NIH-T32DK110966; University of Utah Seed Grant-10060570, Ben B. and Iris M. Margolis Foundation