A prospective study of the association of weekend catch-up sleep and sleep duration with mortality in middle-aged adults

Sleep duration irregularity and risk for incident cardiovascular disease in the UK Biobank

Background

Emerging evidence supports a link between circadian disruption as measured by higher night-to-night variation in sleep duration and increased risk of cardiovascular disease (CVD). It remains unclear whether this association varies by CVD types or may be modified by average sleep duration and genetic risk for CVD.

Methods

Our prospective analysis included 86,219 UK Biobank participants who were free from CVD when completing 7 days of accelerometer measurement in 2013-2016. Sleep irregularity was evaluated by the standard deviation (SD) of accelerometer-measured sleep duration over 7 days. Incident major CVD events, defined as fatal or nonfatal myocardial infarction (MI) and stroke, were identified through linkage to Hospital Episode Statistics data until May 31, 2022. Multivariable-adjusted Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% CIs for associations of sleep duration SD with risk for major CVD events overall and for MI and stroke separately.

Results

We documented 2,310 incident cases of major CVD events (MI: 1,183, stroke: 1,175) over 636,258 person-years of follow-up. After adjusting for sociodemographic factors and family history of CVD, the HR (95% CI) associated with a 1-hour increase in sleep duration SD was 1.19 (1.10, 1.27) for CVD (p-trend<0.0001), 1.23 (1.11, 1.35) for MI (p-trend<0.0001), and 1.17 (1.05, 1.29) for stroke (p-trend=0.003). Additional adjustment for lifestyle factors, co-morbidities and sleep-related factors modestly attenuated these associations. Higher sleep irregularity was associated with higher CVD risk irrespective of genetic risk (p-interaction=0.43), but this association was stronger among individuals with longer average sleep duration >8 hours (p-interaction=0.006).

Conclusions

Higher night-to-night variation in accelerometer-measured sleep duration was associated with consistently higher risks for major CVD events. The association did not seem to be modified by genetic risk for CVD and was more pronounced in long sleepers.

Racial and ethnic disparities in self-reported sleep duration: Roles of subjective socioeconomic status and sleep norms

OBJECTIVES

There are racial and ethnic disparities in sleep duration, with members of historically marginalized groups typically reporting shorter sleep than White Americans. This study examines subjective social status (SSS) as a moderator, and variation in ideal sleep norms as a mediator, of differences in sleep duration between racial/ethnic groups.

METHODS

Asian, Black, Hispanic, and non-Hispanic White respondents in an online survey reported their typical weeknight and weekend-night sleep duration, along with estimates of ideal sleep duration norms. Objective and subjective indicators of socioeconomic status were also assessed. A conditional process analysis was used to examine whether racial or ethnic differences in sleep duration were a) moderated by SSS and b) mediated by ideal sleep duration norms.

RESULTS

Racial/ethnic disparities in sleep duration varied by group. Hispanic participants reported shorter weeknight sleep than White participants. In Asian and Black participants, shorter weeknight sleep relative to White participants was only observed at medium (Black) or high (Black and Asian) levels of SSS. Shorter norms for ideal sleep duration partially mediated differences in sleep duration between Black and White adults, but not the other racial/ethnic groups. There was no evidence of moderated mediation. Neither income nor education moderated racial/ethnic disparities in sleep duration.

CONCLUSIONS

Racial and ethnic disparities in sleep duration may partially depend on SSS. Continued research into moderators and mediators of racial/ethnic differences in sleep duration is warranted.