STUDY OBJECTIVES: To determine effects of yoga and aerobic exercise compared with usual activity on objective assessments of sleep in midlife women. METHODS: Secondary analyses of a randomized controlled trial in the Menopause Strategies: Finding Lasting Answers for Symptoms and Health (MsFLASH) network conducted among 186 late transition and postmenopausal women aged 40-62 y with hot flashes. Women were randomized to 12 w of yoga, supervised aerobic exercise, or usual activity. The mean and coefficient of variation (CV) of change in actigraph sleep measures from each intervention group were compared to the usual activity group using linear regression models. RESULTS: Baseline values of the primary sleep measures for the entire sample were mean total sleep time (TST) = 407.5 +/- 56.7 min; mean wake after sleep onset (WASO) = 54.6 +/- 21.8 min; mean CV for WASO = 37.7 +/- 18.7 and mean CV for number of long awakenings > 5 min = 81.5 +/- 46.9. Changes in the actigraphic sleep outcomes from baseline to weeks 11-12 were small, and none differed between groups. In an exploratory analysis, women with baseline Pittsburgh Sleep Quality Index higher than 8 had significantly reduced TST-CV following yoga compared with usual activity. CONCLUSIONS: This study adds to the currently scant literature on objective sleep outcomes from yoga and aerobic exercise interventions for this population. Although small effects on self-reported sleep quality were previously reported, the interventions had no statistically significant effects on actigraph measures, except for potentially improved sleep stability with yoga in women with poor self-reported sleep quality.