Sleep is a critical factor in the promotion of mental and physical health. Advancing age is associated with progressive decline in sleep efficiency. Critically, poor sleep efficiency is related to diminishing memory performance in healthy older adults and is a key symptom of cognitive impairment. With the rapidly growing aging population, there is an urgent need to identify evidence-based strategies to improve sleep efficiency in older adults. Physical exercise is a promising lifestyle factor to enhance sleep quality. However, the optimal dose of exercise for maximal sleep quality benefits remains unclear. We examined the dose-response relationship between exercise intensity and sleep quality in healthy older adults. Thirty-four participants were randomized into a high-intensity, moderate-intensity, or low-intensity exercise group. Each group received supervised training three times per week for 12 weeks. Subjective sleep quality was assessed at baseline and at study completion. Results demonstrate that moderate-intensity exercise improved sleep efficiency significantly more than high-intensity exercise (p < .05). Total sleep duration was not affected by the intervention. Overall, the results suggest that moderate intensity exercise may be the optimal dose for improving sleep quality in older adults. Ultimately, this research will help to inform exercise prescription guidelines for older adults to enhance sleep quality, cognition and physical health in advancing age.