Daylight Saving Time (DST) began in the United States on Sunday, March 9, 2025, at 2:00 a.m., marking the annual "spring forward" transition. At this time, clocks were moved forward by one hour to 3:00 a.m., resulting in a loss of one hour of sleep for many. This adjustment shifts daylight to the evening, meaning sunrise and sunset occur an hour later than the previous day. The practice is rooted in the idea of maximizing natural light during waking hours, offering longer evenings for activities while conserving energy. Most states in the U.S. observe DST, except Hawaii and parts of Arizona, along with U.S. territories like Puerto Rico and Guam.

The concept of DST has been a part of American life since its formal adoption in 1966 under the Uniform Time Act. While it was initially introduced to save energy during World War I, its modern implementation is more about lifestyle benefits than energy conservation. The current schedule, established by the Energy Policy Act of 2005, extends DST from the second Sunday in March to the first Sunday in November. Despite its widespread use, DST has faced criticism and legislative challenges, with some lawmakers proposing to make it permanent to avoid biannual clock changes.

The time change has notable effects on daily life and health. The "spring forward" transition often disrupts sleep patterns, leading to a temporary loss of sleep that can increase risks for heart attacks, strokes, and traffic accidents in the days following the change. On the positive side, longer evening daylight is associated with increased outdoor activities and economic benefits for certain industries like retail and tourism. However, critics argue that these advantages do not outweigh the health and safety concerns linked to disrupted circadian rhythms.

For devices like smartphones and computers, the time change happens automatically. However, analog clocks and other manual devices need to be adjusted by hand. To ease into the transition, experts recommend gradually shifting bedtime earlier in the days leading up to DST. As clocks move forward an hour on March 9, Americans will enjoy extended daylight hours through summer until DST ends on Sunday, November 2, 2025, when clocks will "fall back" by an hour.