Rest-activity pattern, which describes the physical activity and sleep behaviors of individuals, was reported to be related to some common diseases, such as depression and dementia, by observational studies. However, these relationships may be weakened by the major limitations of observational studies, involving reverse causation, confounding effects and unreliable assessment tools. Therefore, the causal effects of rest-activity patterns on theses common diseases are still unknown. Therefore, we intend to study causal effects of rest-activity pattern changes on these common diseases. This project will last for 36 months. Findings from this research may establish causal effect of rest-activity pattern on common diseases. These findings will pave a way for future preventive strategies for most common diseases by modifying lifestyle, such as promoting physical exercise.