Multi-task exercise increases delta power in non-rapid eye movement sleep among older female adults: A randomized crossover trial

Delta power in electroencephalography during sleep has been used as a more quantitative approach to determine sleep depth and quality. Despite the positive effects of both exercise and cognitive activity on delta power during sleep, limited information is available regarding the effects of multi-task exercise, which combines these two activities. Therefore, this study aimed to investigate the impact of multi-task exercise on delta power during sleep. Fifteen older female adults participated in both multi-task and single-task exercises at low and moderate-to-vigorous intensities for 30 min each. Sleep architecture was recorded using polysomnography to compare the amount of delta power during sleep. Additionally, cortical hemodynamic changes in the prefrontal cortex were monitored using functional near-infrared spectroscopy before and after each exercise session. Low-intensity multi-task exercise increased cortical activation in the right and left ventrolateral prefrontal cortex and frontopolar area, which positively correlated with the increase in delta power. This study provides the first experimental evidence that low-intensity multi-task exercise enhances cortical activation in the prefrontal cortex of older female adults, leading to an increase in delta power during sleep. It also suggests that low-intensity multi-task exercise may be a more useful intervention for improving sleep quality in older adults.