Abstract
Psychological stress can lead to nocturnal hyperarousal and sleep disruption. However, the extent to which habitual physical activity buffers stress-related effects on sleep and hyperarousal remains unclear. PURPOSE: The purpose of this study was to examine whether habitual physical activity moderates the relationship between habitual stress, sleep duration, and nocturnal heart rate (HR). We hypothesized that habitual physical activity would moderate the relationship between stress, sleep, and HR. Specifically, higher stress would be associated with shorter total sleep time and elevated HR primarily among individuals with lower physical activity, whereas more physically active individuals would experience smaller stress-related reductions in sleep duration and increases in HR. METHODS: Thirty-nine young adults (age: 21 ± 4 [range: 18-33 years], BMI: 23 ± 4 kg/m²) participated in this observational study where data was collected on objective sleep measures, including total sleep time (TST), average nocturnal HR, and heart rate variability (HRV) using Oura rings across consecutive nights (Avg: 15 ± 2 nights). Habitual physical activity was quantified using average daily step counts from the Oura ring monitoring. Daily stress was assessed every evening using a 7-point Likert scale, in which participants reported how stressful their day was, ranging from 1 (not at all stressful) to 7 (extremely stressful). Participant level averages were calculated across all variables. We then used moderation analysis to determine whether daily step count moderated the association between average stress, nightly sleep, and HR. RESULTS: Daily stress was positively associated with average nocturnal heart rate (r=0.318, p=0.049), but not TST (r= 0.037, p=0.824). Moderation analysis demonstrated a nonsignificant moderation of daily step count on the association between stress and nocturnal HR (p=0.108). However, exploration of conditional effects revealed a significant positive association between stress and nocturnal heart rate at lower daily step counts (≈6,158 steps/day; p=0.031), with attenuated and non-significant associations at moderate (≈8,942 steps/day; p=0.113) and high (≈13,027 steps/day; p=0.978) step counts. Additionally, and consistent with these findings, a tertile analysis demonstrated the strongest stress–heart rate association in the lowest step count tertile (r=0.502, p=0.081), with weaker associations in the middle (r=0.185, p=0.545) and highest (r=−0.049, p=0.873) tertiles. CONCLUSION: Overall, daily stress was associated with an elevated nocturnal heart rate, but there was not a statistically significant moderation of daily step count on the association between stress and nocturnal HR. However, further preliminary exploration of both moderation and tertile analyses provide some trend-level support that higher habitual physical activity could attenuate vulnerability to stress-related increases in nocturnal heart rate, but a larger sample size is necessary to reach a more rigorous conclusion.
Recommended Citation
Becker, Joelle; Bigalke, Jeremy A.; and Carter, Jason R.
(2026)
"Habitual Physical Activity Moderates the Association Between Psychological Stress and Nocturnal Heart Rate in Young Adults,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
18, Article 114.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss18/114