Short bouts of physical activity enhance feelings of energy and improve well-being. Circadian rhythm strongly influences mood, but its impact on the association of physical activity and mood is unknown. Intensive longitudinal data were obtained from two independent samples (Ns = 106 and 68), each comprising two groups characterized by distinct manifestations of physical activity and energy: participants with depression (nStudyA = 53; nStudyB = 32) and healthy participants (nStudyA = 53; nStudyB = 36). Participants reported their feelings of energy repeatedly across the day; physical activity was self-rated (Study A) or measured via accelerometers (Study B). Multilevel modeling with three-way moderation analyses was used to test the association of physical activity with feelings of energy as a function of time of day and depression. Across studies, physical activity was consistently related to feelings of energy throughout the day for healthy participants. In contrast, in participants with depression, the relation between physical activity and energy decreased across the day. That participants with depression only felt more energized from physical activity in the morning could be an important starting point for considering circadian rhythm in physical activity interventions for depression. Although the missing ethnicity information from Sample B and high education across samples constrain the generalizability of our findings, the within-person associations nevertheless likely provide relevance for clinical populations and further underscore the potential of intensive longitudinal naturalistic methods to understand complex multidimensional relationships. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
