Daily reciprocal relationships between affect, physical activity, and sleep in middle and later life

The daily dynamics among affect, physical activity, and sleep are often explored by taking a unidirectional approach. Yet, obtaining a comprehensive understanding of the reciprocal dynamics among affect and health behaviors is crucial for promoting daily well-being. This study examined the reciprocal associations among affect, physical activity, and sleep in daily life in a U.S. national sample of mid- and later-life adults. The study sample included 1,171 participants (mean age = 62.61 years, SD = 10.26 years, 57% female, 82% White) with 9,033 daily interview days from the daily diary project of the third wave of the Midlife in the United States study (MIDUS III). Participants reported their daily experiences across eight consecutive days. Using a dynamic structural equation modeling, we examined day-to-day autoregressive and cross-lagged associations among positive and negative affect, physical activity, and sleep. Results revealed that higher positive affect predicted a greater likelihood of engaging in moderate-to-vigorous physical activity (MVPA) and better sleep quality the following day. Higher sleep quality predicted increased positive affect, reduced negative affect, and a greater likelihood of MVPA engagement the next day. Longer sleep duration predicted lower negative affect the following day. However, MVPA engagement predicted subsequent higher negative affect. Findings underscore the importance of simultaneously considering affect, physical activity, and sleep in studying their day-to-day dynamics, and the protective role of positive affect and sleep quality in daily life. Maintaining high positive affect and managing sleep quality may be important intervention targets for enhancing daily well-being.