First Advisor

Hayward, Reid

First Committee Member

Stewart, Laura

Second Committee Member

Haughian, James

Third Committee Member

Han, Yuyan

Degree Name

Doctor of Philosophy

Document Type

Dissertation

Date Created

12-2025

Department

College of Natural and Health Sciences, Kinesiology Nutrition and Dietetics, KiND Student Work

Abstract

Poor sleep quality and circadian rhythm disruption are commonly reported among cancer survivors and may contribute to worsened health outcomes, including increased fatigue, psychological distress, and reduced quality of life. While some recent studies suggest that exercise can improve sleep and circadian regulation in cancer survivors, limited research exists on how the timing of this exercise affects these outcomes in cancer survivors. The purpose of this study was to examine the effects of a 12-week supervised exercise intervention, performed either in the morning (AX) or evening (PX), on functional capacity, subjective and objective sleep quality, and peripheral markers of circadian rhythm (salivary melatonin and cortisol). A secondary aim was to determine whether circadian hormone changes correlated with improvements in sleep-related outcomes. Forty-four cancer survivors (60.9 ± 10.3 years of age) participated in an exercise intervention. A subgroup of 24 subjects wore a WHOOP 4.0 activity monitor to quantify objective sleep quality (e.g., HRV, sleep efficiency, sleep stages) and completed a subjective sleep survey (PSQI). Salivary melatonin and cortisol samples were collected across 9 time points over a 48-hour period pre- and post-intervention for a subset of participants (n = 8). Both AX and PX groups showed significant improvements in multiple functional outcomes, including VO₂peak, muscular strength, and muscular endurance. However, the AX group demonstrated greater improvements in subjective sleep quality (PSQI: - 3.76 ± 0.08), heart rate variability (HRV: +8.01 ± 6.30 ms), and depressive symptoms (BDI: -4.86 ± 5.72), whereas the PX group experienced declines in both subjective sleep (PSQI: +3.39 ± 1.83) and HRV (-4.49 ± 6.78 ms) over the intervention period. While group-level changes in circadian hormone parameters were not statistically significant, strong correlations were observed between changes in cortisol (mesor: r = - 0.788; amplitude: r = -0.756) and melatonin parameters (acrophase shift and deep sleep time: r = -0.913; acrophase shift and sleep efficiency: r = -0.845) and improvements in sleep quality and physiological recovery (WHOOP sleep score, r = 0.816). These findings suggest that morning exercise may be more effective in enhancing sleep quality and psychological recovery in cancer survivors, and that individual-level circadian hormone shifts may play a role in mediating these improvements. While group-level circadian markers remained largely unchanged, strong individual-level associations between circadian hormone shifts and sleep outcomes indicate that exercise timing may be an important determinant of recovery in cancer patients undergoing or recovering from treatment.

Abstract Format

html

Language

English

Extent

96 pages

Rights Statement

Copyright is held by the author.

Digital Origin

Born digital

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