Stress, positive affect, and sleep in older African American adults: a test of the stress buffering hypothesis.

backgroundAlthough sleep disparities contribute to racial health disparities, little is known about factors affecting sleep among African Americans. One such factor may be positive affect, which could impact sleep directly (direct effect hypothesis) or indirectly by buffering the effects of stress (stress buffering hypothesis). PURPOSE: We tested the direct effect and stress buffering effects of positive affect on sleep at three levels (day, week, trait) in a sample of 210 older African American adults, ranging in age from 50 to 89 years old.

methodDaily positive affect, perceived stress, sleep quality, and sleep duration were collected for five consecutive days. Multilevel modeling was used to test the direct and stress buffering hypotheses both within-person (day level) and between-persons (week level). Trait positive affect, past five-year stress severity, and global sleep quality were assessed cross-sectionally. Regression was used to test the direct and stress buffering hypotheses at the trait level.

resultsIn line with the direct effect hypothesis, higher week-level positive affect predicted better sleep quality and sleep duration. Day-level positive affect was not significantly associated with daily sleep quality or daily sleep duration. Higher trait positive affect predicted better global sleep quality. However, neither day-level perceived stress nor past five-year stress severity significantly interacted with positive affect measures for any sleep outcome; no interaction effect was observed on week-level sleep duration. Positive affect and perceived stress interacted at the week level to predict sleep quality, but not in the hypothesized direction.

conclusionsWe found support for the direct effect hypothesis at the week- and trait-levels, but not at the day level. In contrast, we found no support for the stress buffering hypothesis.