Date of Award

2016

Document Type

Open Access Dissertation

Department

Exercise Science

Sub-Department

The Norman J. Arnold School of Public Health

First Advisor

Xuewen Wang

Abstract

Sleep is a modifiable behavior that commonly fluctuates from night to night within the same individual and varies across the lifespan. Over the years, sleep research has identified physical activity (PA)/exercise as a non-pharmacological approach to improving sleep. The overall goal of this dissertation was to investigate the acute effect of exercise on sleep outcomes as well as examine the relationship between night-to-night fluctuations in sleep parameters with exercise training among healthy older women.

Two studies, both utilizing a longitudinal study design, were conducted to 1) understand how acute exercise affects both behavioral and physiological sleep outcomes during the corresponding night among trained older women and 2) to determine whether 4 months of moderate-intensity exercise impacts night-to-night variability in sleep among older women. Data collected from the WEWALK study, a clinical exercise trial involving older women, were used in both studies. Multiple assessments of sleep parameters were objectively measured via actigraphy at baseline, mid-intervention, and post-intervention and cardiorespiratory fitness levels using a graded treadmill test at baseline and post-intervention.

The first study found that behavioral sleep parameters were significantly impacted by structured exercise in which bedtimes were significantly earlier on nights following a day of structured exercise versus bedtimes on days with no structured exercise. No significant differences were observed between structured exercise versus non-structured exercise days in any of the physiological (i.e. total sleep time [TST], sleep onset latency [SOL], wake time after sleep onset [WASO], number of awakenings, and activity counts) sleep parameters.

In the second study, there was a borderline to significant time effect observed for WASO and number of awakenings for both measures of variability at post-intervention, which may indicate more consistent sleep over several nights with a possible improvement to sleep quality. Additionally, higher VO2peak levels at baseline were associated with a shorter amount of time in bed and lower night-to-night variability in TST throughout the exercise intervention.

Overall, this dissertation found that acute exercise bouts significantly influenced behavioral sleep parameters in healthy, trained older women, and that nightly variability in WASO and number of awakenings was observed to decrease with exercise training over time. These changes in nightly variability suggest possibly greater consistency with improved sleep quality. Collectively, exercise affects sleep acutely and chronically. However, the health implications of the demonstrated changes need further investigation.

Rights

© 2016, Charity B. Breneman

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