Clocks in most of the U.S. skipped ahead one hour at 2 a.m. on Sunday, March 9, to begin daylight saving time [1].
This annual transition matters because the shift in sleep patterns and morning light exposure is linked to significant public health outcomes. While some reports suggest the practice can lower energy bills by up to $775 [2], epidemiological data indicates the biological cost may outweigh the financial gain.
The transition creates a 23-hour day [3] that disrupts human circadian rhythms. By shifting clocks forward, the practice results in darker mornings and a loss of about one hour of sleep [4]. This lack of early morning light and reduced rest can have systemic effects on the body.
Epidemiological studies link these changes to poorer metabolic health, specifically higher rates of obesity and diabetes [5]. The disruption of sleep schedules and the reduction of light entering the eyes during the morning hours are cited as primary drivers of these adverse health outcomes [5].
"Losing that hour of sleep can do more than leave you tired and cranky the next day; it also could harm your health," an Associated Press reporter said [6].
These health risks are particularly pronounced for populations living on the western edge of U.S. time zones [7]. Because these areas are the furthest from the eastern boundary of their zone, the clock shift results in the most significant delay of natural sunrise relative to the clock time.
Despite these findings, the practice continues as scheduled each year. The transition begins on the second Sunday in March and ends on the first Sunday in November [8]. While many officials and citizens have pushed to eliminate the shift, no immediate policy changes have been implemented to stop the cycle.
“Losing that hour of sleep can do more than leave you tired and cranky the next day; it also could harm your health.”
The tension between the economic incentive of energy savings and the biological necessity of circadian alignment suggests that DST is a policy based on outdated industrial needs. For those on the western edges of time zones, the artificial shift creates a misalignment between social time and biological time, potentially increasing the long-term risk of chronic metabolic diseases.
