Abstract
Abstract
Introduction
Several studies have demonstrated population-level disparities in sleep duration and sleep quality. Population-level estimates of bedtime and waketime have been unavailable. Considering the important role of circadian rhythms in health, population-level disparities in timing have important public health implications.
Methods
Data from the 2015-2016 National Health and Nutrition Examination Survey (NHANES) from the CDC were used (N=4,491). Typical time in and out of bed were assessed and were converted to minutes. Race/ethnicity was self-reported and coded as non-Hispanic White, Black/African-American, Mexican-American, Other Hispanic/Latino, Asian, and Multiracial/Other. Covariates included age, sex, education level, income/poverty ratio, body mass index, and overall health. Additional models controlled for habitual sleep duration, frequency of sleep disturbance, depressed mood, and daytime tiredness/fatigue. Multiple linear regression analyses with time as an outcome were weighted using CDC-provided NHANES sample weights.
Results
In adjusted analyses, compared to non-Hispanic Whites, Blacks/African-Americans went to bed 29.4 mins later (p<0.0005), Asians went to bed 37.0 mins later (p<0.0005) and woke 27.7 mins later (p<0.0005), and Mexican-Americans woke 16.3 mins earlier (p=0.018). After further adjustment for sleep duration and sleep disturbances, Blacks/African-Americans went to bed 22.1 mins later (p<0.0005) and woke 22.2 mins later (p<0.0005), and Asians went to bed 36.1 mins later (p<0.0005) and woke 40.6 mins later (p<0.0005). These relationships remained generally unchanged when depressed mood and daytime tiredness/fatigue were adjusted in the model.
Conclusion
This is the first nationally-representative study to demonstrate population-level disparities in sleep timing. Specifically, Blacks/African-Americans and Asians present with delayed sleep, even after adjusting for other aspects of sleep.
Support
Dr. Grandner is supported by R01MD011600