The Effect Of Short-term Exercise On Sleep And Daytime Impairment In Adults With Insomnia

Evidence suggests acute exercise is related to improved sleep quality, though research is largely limited to normal sleepers. Whether acute exercise impacts sleep and daytime impairment in samples of adults with insomnia disorder remains unclear. Methods: Following a baseline sleep and physical activity monitoring week, 24 participants with insomnia (70.8% white, 70.8% female, age: 33.7±9.8 y, body mass index: 25.8±4.0 kg/m2) were randomized to one of two experimental conditions that took place on three non-consecutive days over a week-long observation period: 1) moderate-intensity exercise (i.e., 30-minute walks performed at 50% of heart rate reserve); or 2) quiet rest (i.e., watching documentaries while seated). Daily sleep behavior was collected using a diary and wrist-worn actigraphy. Subjective pre-sleep arousal was measured in the diary (i.e., Pre-sleep Arousal Scale (PSAS)). Insomnia severity, daytime impairment, and sleep quality were assessed at the end of the baseline and experimental weeks with the Insomnia Severity Index, PROMIS Sleep-related Impairment scale, and PROMIS Sleep Disturbance scale, respectively. Exercise sessions were monitored with a heart rate monitor and self-report; quiet rest sessions were monitored via video calls. Repeated measures analysis of variance (ANOVA) models were used to examine mean-level differences in sleep between weeks with interactions by condition. Linear mixed effect models examined day-level associations between PSAS and sleep and the difference in sleep behavior on nights following exercise versus non-exercise days. Results: Both experimental groups showed reduced insomnia severity and daytime impairment between weeks (p<0.01), with no interactions by condition over time (p>0.35). Inconsistent within-group improvements in sleep behavior were found, with no condition x time interactions observed (p>0.086). Day-level analyses found an association between pre-sleep arousal and sleep (actigraphy-based sleep efficiency [mean±standard error]: B=-0.3±0.1%, p=0.030; actigraphy-based wake after sleep onset: B=1.6±0.5 min, p=0.048; sleep quality B=-0.1±0.2, p=0.001). Sleep parameters were significantly improved following exercise versus non-exercise days (actigraphy-based total sleep time: B=0.9±0.4 h, p= 0.032; diary-based total sleep time: B=0.8±0.4 h, p= 0.049; diary-based morning restedness: B=0.5±0.2, p=0.019). Conclusions: In participants with insomnia, acute exposure to walking exercise may not elicit global improvements in sleep and daytime function, though sleep may improve the night after exercise sessions.