Helping the family may either promote or undermine adolescents' physical health and well-being. Adolescents (N = 396, 58% female, M[subscript age] = 14.57 years) completed diary checklists for 14 days, reporting whether they provided instrumental assistance (e.g., tangible tasks) and emotional support (e.g., listening, giving advice) to family, as well as their amount of physical activity, sleep, and physical symptoms (e.g., headache, backpain) each day. After providing emotional support, adolescents slept more that night and experienced fewer physical symptoms the next day, over and above prior day levels. When adolescents provided instrumental assistance on school days (but not non-school days), they engaged in less physical activity that day. These results were consistent across individual differences in gender, age, socioeconomic status, and ethnicity. In addition, bidirectional associations emerged such that adolescents were more likely to provide instrumental assistance on days after they slept more. [This paper was published in "Journal of Family Psychology" v35 n7 p875-885 2021.]