["American Journal of Human Biology, Volume 38, Issue 6, June 2026. ", "\nABSTRACT\n\nBackground\nThe 24 h movement behavior cycle (24hMB) has been increasingly studied in older adults. However, longitudinal changes in the 24hMB cycle and its potential correlates are poorly understood, particularly in low to middle‐income countries. This study investigated longitudinal changes of 24hMB and their potential correlates in Brazilian older adults.\n\n\nMethods\nThe 24hMB was assessed in community‐dwelling older adults aged 60–80 years using hip accelerometry (ActiGraph GT3X+) over 1 week at baseline and follow‐up. Outcomes included nocturnal sleep time (NST), sedentary time, light physical activity (LPA), and moderate‐to‐vigorous physical activity (MVPA). Longitudinal changes and associations between changes in 24hMB and potential baseline correlates (age, sex, body mass index, post‐secondary education, and multimorbidity) were examined using generalized estimating equations.\n\n\nResults\nA total of 86 participants were analyzed (67.4 ± 5.3 years; mean follow‐up: 4.0 ± 0.4 years). No changes were observed in NST (p > 0.05). However, sedentary time increased (36 ± 86 min/day), while LPA (16 ± 63 min/day) and MVPA (9 ± 20 min/day) decreased over 4 years (p < 0.05). Older age was associated with reduced NST and increased sedentary time over time. Female sex was associated with reduced NST and increased sedentary time and MVPA. No associations were found between multimorbidity, BMI, and education level and changes in 24hMB (p > 0.05).\n\n\nConclusion\nAfter a 4‐year period, older adults experienced an overall increase in sedentary time and a decrease in physical activity, while NST remained stable. The correlates associated with changes in NST, sedentary time, and physical activity may help inform targeted interventions to improve 24hMB.\n\n"]