Bittersweet Transition: Sex- and Lineage-Specific Changes in Sleep Duration and Timing Across First-Time Grandparenthood

OBJECTIVES: Although prior research links first-time grandparenthood to changes in well-being in mid- and later life, little is known about how sleep duration and timing change across this transition. Guided by a life-course perspective, we examine within-individual changes in sleep duration, sleep onset timing, and nap duration around entry into grandparenthood among women and men. METHODS: Using six waves of longitudinal data from the China Family Panel Studies (CFPS, 2010-2022), we estimate fixed-effects models with event-time indicators to trace sleep trajectories before and after the transition. RESULTS: Nighttime sleep duration declines after the transition to grandparenthood, with more sustained reductions among men than women. Among men, sleep duration decreases from the birth year and remains lower for up to nine years. Among women, declines are smaller and limited to specific post-transition years. We find little evidence of changes before the transition. Sleep onset timing and nap duration remain stable. Stratified analyses show differences by grandparental sex and parental lineage. Reductions are concentrated in the maternal lineage, particularly among non-employed maternal grandmothers and non-coresiding maternal grandfathers. Maternal grandfathers show declines shortly after the transition, regardless of employment status. Employment status and living arrangement otherwise show limited moderating effects. DISCUSSION: The transition to grandparenthood is associated with differentiated changes in sleep duration, showcasing the value of an intersectional life-course approach for understanding sleep in middle and later adulthood.