Effect of Improved Sleep Regularity on Subendocardial Viability Ratio in Young to Middle-Aged Adults

Authors

Gabriel Narvaez, Texas Tech UniversityFollow
Joaquin Gonzales, Texas Tech UniversityFollow

Abstract

Fluctuation of the sleep/wake schedule, commonly referred to as sleep irregularity, is associated with increased risk of cardiovascular disease (CVD). Subendocardial viability ratio (SEVR) is a measure of myocardial perfusion relative to left-ventricular oxygen demand and holds clinical value as a predictor of adverse CVD events. However, little is known on how sleep irregularity could affect SEVR. PURPOSE: To test the hypothesis that a reduction in sleep irregularity would improve SEVR. METHODS: Fourteen adults (9F, 5M, age 35.43 ± 10y, BMI 25.46 ± 3.60 kg/m²) participated in a randomized crossover study that included 12 nights of a consistent sleep/wake schedule and 12 nights of habitual sleep separated by a 1 to 2-week washout period between conditions. Sleep was assessed at-home by wrist actigraphy throughout the study. Radial artery applanation tonometry was used to derive central aortic blood pressure waveforms for calculation of SEVR. At least three tonometry measurements with operator indices greater than 90% were obtained at each time point, and the average of the two highest quality measures were used for analysis. Two-tailed paired t-tests and Wilcoxon Signed Rank tests were used for comparisons between habitual and consistent sleep conditions. Normally distributed data are presented as mean ± SD and asymmetrically distributed data as median (interquartile range). RESULTS: The standard deviation of sleep duration across all 12 nights (i.e., sleep irregularity) was reduced following consistent sleep as compared to habitual sleep (55.29 ± 15.17 to 33.86 ± 13.33 min, p<0.001) with there being no change in average sleep duration (p>0.05). Consistent sleep increased SEVR (1.54 ± 0.22 to 1.71 ± 0.32, p<0.001). The change in SEVR was due to a lowered resting heart rate (65.71 ± 8.15 to 62.00 ± 9.46 bpm, p=0.006) that resulted in a greater diastolic time (596.71 ± 120.78 to 655.85 ± 151.08 ms, p=0.003) and diastolic/systolic time ratio (1.77 ± 0.30 to 1.92 ± 0.36, p=0.003) following the consistent sleep condition. There were no significant differences (p>0.05) in systolic time, aortic mean diastolic pressure, aortic mean systolic pressure, or aortic mean diastolic/systolic pressure ratio between sleep conditions. CONCLUSION: These results indicate that reduced sleep irregularity can improve SEVR by altering timing for myocardial perfusion. This finding provides important insight into how having a consistent sleep schedule may potentially reduce future CVD risk.

Recommended Citation

Narvaez, Gabriel and Gonzales, Joaquin (2025) "Effect of Improved Sleep Regularity on Subendocardial Viability Ratio in Young to Middle-Aged Adults," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 17, Article 2.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss17/2