Daylight Saving Time: Why Are We Still Changing the Clock?

DST is the seasonal practice of advancing clocks—typically by one hour during the warmer months—to extend evening daylight. Originally implemented during World War I as an energy‐conservation measure, DST was later adopted by many countries as a means of better aligning human activity with daylight hours. Early analyses in the peer‐reviewed literature place its origins within broader efforts to reduce energy consumption during times of scarcity .

The Reflective American