Sleep is a fundamental health behavior that has profound implications for an individual's well-being. Worry has been recognized as a major cause of sleep problems, but it remains unclear how middle-aged adults' worries about their adult children and aging parents are associated with their sleep on a daily basis. Middle-aged adults (N = 191; Mage = 55.93) were interviewed for 7 consecutive days (Nday = 1,261). Participants reported on the time they went to bed, the time they woke up, and the quality of sleep on each interview day. Daily interviews also assessed participants' worries about each adult child (n = 454) and each aging parent (n = 253). Multilevel models showed that middle-aged adults' prior day's worries about adult children were associated with poorer sleep quality that night. After they experienced a good night's sleep, middle-aged adults were less likely to worry about their parents. Findings suggest a daily link between worries about family members and sleep among middle-aged adults. Worries about family members are associated with poorer sleep quality at night; poorer sleep quality is related to an increased risk of worrying about family members on the subsequent day. Our findings suggest the development and implementation of interventions to promote sleep health in multigenerational families is warranted. (PsycINFO Database Record (c) 2020 APA, all rights reserved).