Free Day, but Not Work Day, Sleep Duration Is Inversely Associated With Aortic Stiffness in Apparently Healthy Young Adults
Authors: Lincoln Zoe R. , Cross Brett L. , Vondrasek Joseph D. , Frederick Josiah M. , Blumenburg Wesley T. , Gaither Peter , Chall Amy , Bryan Anna , Bock Joshua M. , Flatt Andrew A. , Robinson Austin T. , Grosicki Gregory J. 
Published: May 2022

Insufficiency or irregularity in sleep is associated with high blood pressure (BP) and aortic stiffness, both of which are independent predictors of all‐cause and cardiovascular mortality. The cardiovascular ramifications of short and irregular sleep are well documented in shift workers, but the health implications of possible differences between sleep duration on workdays (WD) and free days (FD) in non‐shift workers is less clear.

PURPOSE

We sought to examine associations between WD and FD sleep duration, and then to inspect for relationships between WD and FD sleep duration, as well as the difference between WD and FD sleep duration (i.e., sleep irregularity), with BP and indices of arterial stiffness in apparently healthy young adults. We hypothesized 1) participants would sleep less on WD than FD, and 2) that participants with short WD sleep duration would exhibit higher BP and arterial stiffness, and 3) those with greater sleep irregularity would exhibit higher BP and arterial stiffness.

METHODS

16 apparently healthy young adults (21.8±4.0 yrs; 24.4±2.9 kg/m2; Mean±SD) participated in this study. All participants completed the Munich ChronoType Questionnaire to assess self‐described WD and FD sleep‐wake behavior. WD and FD sleep duration were determined, and sleep irregularity was quantified as the absolute value of the difference between WD and FD sleep duration. Following 10‐min of supine rest, we used an automated oscillometric device (SphygmoCor XCEL) to measure BP and augmentation index (AIx), an indirect measure of arterial stiffness. Aortic stiffness was then assessed using carotid‐femoral pulse wave velocity (cf‐PWV). WD and FD sleep duration were compared using a paired t‐test and associations between sleep with BP and indices of arterial stiffness were assessed using Pearson correlations, or the non‐parametric equivalent for sleep irregularity.

RESULTS

WD sleep duration was 492±85 min, FD sleep duration was 480±83 min, and sleep irregularity was 53±49 min. Systolic BP was 120±10 mmHg, diastolic BP was 68±7 mmHg, AIx was 10.9±9.8 %, and cf‐PWV was 5.8±0.7 m/s. WD sleep duration was significantly greater (P<0.01) than FD sleep duration, and WD sleep duration was not associated (P>0.05) with systolic BP (r=0.10), diastolic BP (r=0.10), AIx (r=0.07), or cf‐PWV (r=‐0.18). FD sleep duration was inversely correlated with cf‐PWV (r=‐0.65; P=0.01), but was not associated (P>0.05) with systolic BP (r=‐0.12), diastolic BP (r =‐0.08), or AIx (r=0.25). Sleep irregularity was not associated (P>0.05) with systolic BP (r=0.37), diastolic BP (r=0.45), AIx (r=0.08), or cf‐PWV (r=0.14).

CONCLUSIONS

Contrary to our hypothesis, FD, but not WD, sleep duration was associated with aortic stiffness in apparently healthy young adults. Average sleep duration of our cohort exceeded the recommended minimum of 7 hours per night and sleep irregularity was small (i.e., <60 min on average), thus potentially masking elevations in BP and arterial stiffness seen with short and/or irregular sleep such as in shift workers.