Daylight Saving Time (DST) is used worldwide and affects millions of people annually. In the most countries, DST begins turning clocks forward by an hour in the spring and backward by an hour in the fall. transition out of DST in the fall increases the available daylight in the morning by one hour. Springtime transition into DST leads to an increase of the available daylight in the evening. During World War I, in an effort to reduce fuel consumption, Germany and England began to practice DST in 1916. Currently, 77 countries and most of OECD adopted DST except Korea, Japan, Iceland. The rationale for Daylight Saving Time (DST) is bolstered by the fact that it increases daylight hours within which the activity a population reaches its peak. Therefore, the effects of transitions into DST to the public health should be further explored, as DST affects millions of people annually and its impacts are still largely unknown. A general perception is that Turning clock forwards (on spring) or backwards (on fall) by one hour would affect our health. In This study, the association between Daylight Saving Time (DST) and health in population was investigated through theoretical and systemic review studies. Since the study was conducted solely on theoretical grounds, further research is needed to assess additional health-related impacts of Daylight Saving Time (DST) and to carry out more specific analysis on population health in Korea. In conclusion, population health is more strongly affected during spring transition into DST than during fall transition out of DST.