As the United States prepares to “spring forward” this weekend, the long-running debate over Daylight saving time has resurfaced, with scientists and health experts warning that the twice-yearly clock change may have negative effects on human health.
Clocks across most of the country will move forward by one hour at 2 a.m. on Sunday, March 8, marking the beginning of the annual Daylight saving time period that lasts until November. While the shift brings longer daylight hours in the evening, it also means millions of Americans lose an hour of sleep overnight.
Despite increasing criticism from sleep researchers and public health experts, the century-old practice continues largely unchanged.
The idea gained traction during World War I when several countries adopted the practice to conserve fuel and electricity. In the United States, the policy was used intermittently before being formally standardized through the Uniform Time Act of 1966.
Under current rules, Americans move their clocks forward in March and back again in November. The modern schedule, which runs from March to November, has been in place since 2007.
However, the practice is not universal across the country. Hawaii and most of Arizona do not observe Daylight saving time, and the same applies to several U.S. territories, including Puerto Rico, Guam, the U.S. Virgin Islands, Northern Mariana Islands and American Samoa.
Studies cited by medical researchers indicate that the abrupt loss of an hour of sleep can lead to increased stress on the body. According to findings discussed by researchers at Johns Hopkins University, the clock change has been linked to higher risks of heart attacks and strokes in the days following the spring transition, as mentioned in a report by USA Today.
The disruption of sleep patterns can also contribute to mood disturbances and increased hospital admissions. Some researchers have found that stress-related inflammatory markers may rise as the body adjusts to the sudden shift in schedule.
Another concern is road safety. A 2020 study conducted by researchers at the University of Colorado Boulder and the Fred Hutchinson Cancer Research Center found that fatal car crashes increase by about 6 percent in the days immediately after the spring clock change.
Experts say the underlying issue is the disruption of the body’s circadian rhythm, the internal biological clock that regulates sleep and wake cycles.
This shift can make it harder for individuals to fall asleep at their usual bedtime, particularly in the first few days after the clocks change.
Sleep experts explain that the body typically releases melatonin, the hormone responsible for making people feel sleepy, when darkness falls. When sunset occurs later due to the clock adjustment, this natural process may be delayed.
The resulting sleep loss can lead to fatigue, reduced concentration and irritability.
Children who must wake up early for school and shift workers are among the groups most affected by the schedule change. People living on the western edges of time zones may also experience stronger disruptions because sunrise occurs later in the morning.
Over the past decade, several lawmakers have introduced proposals to make daylight saving time permanent or eliminate the seasonal clock change altogether. However, none of these proposals have successfully passed both chambers of Congress.
One frequently discussed proposal, often referred to as the Sunshine Protection Act, aims to make daylight saving time the permanent national standard.
More recently, another legislative effort known as the Daylight Act of 2026 proposes shifting U.S. time zones forward by 30 minutes and keeping them there year-round.
Political leaders remain divided on the issue. Some argue that longer evening daylight benefits businesses and outdoor activities, while others emphasize the health concerns raised by medical researchers.
Public opinion is also split. Some Americans prefer brighter evenings, while others favor more daylight in the early morning hours.
As a result, the clock-changing system has remained in place.
Gradually shifting bedtime earlier by 15 to 20 minutes in the days leading up to the change may help the body adjust more smoothly. Setting clocks forward on Saturday evening rather than waiting until Sunday morning can also reduce confusion.
Experts also suggest spending time outdoors in natural sunlight on the first morning after the change, as early light exposure helps reset the body’s internal clock.
Clocks across most of the country will move forward by one hour at 2 a.m. on Sunday, March 8, marking the beginning of the annual Daylight saving time period that lasts until November. While the shift brings longer daylight hours in the evening, it also means millions of Americans lose an hour of sleep overnight.
Despite increasing criticism from sleep researchers and public health experts, the century-old practice continues largely unchanged.
What Is Daylight Saving Time?
Daylight saving time was originally introduced more than a century ago with the goal of extending evening daylight and reducing energy consumption.The idea gained traction during World War I when several countries adopted the practice to conserve fuel and electricity. In the United States, the policy was used intermittently before being formally standardized through the Uniform Time Act of 1966.
Under current rules, Americans move their clocks forward in March and back again in November. The modern schedule, which runs from March to November, has been in place since 2007.
However, the practice is not universal across the country. Hawaii and most of Arizona do not observe Daylight saving time, and the same applies to several U.S. territories, including Puerto Rico, Guam, the U.S. Virgin Islands, Northern Mariana Islands and American Samoa.
Health Studies Raise Concerns
A growing body of research suggests the transition to Daylight saving time may disrupt sleep patterns and trigger short-term health risks.Studies cited by medical researchers indicate that the abrupt loss of an hour of sleep can lead to increased stress on the body. According to findings discussed by researchers at Johns Hopkins University, the clock change has been linked to higher risks of heart attacks and strokes in the days following the spring transition, as mentioned in a report by USA Today.
The disruption of sleep patterns can also contribute to mood disturbances and increased hospital admissions. Some researchers have found that stress-related inflammatory markers may rise as the body adjusts to the sudden shift in schedule.
Another concern is road safety. A 2020 study conducted by researchers at the University of Colorado Boulder and the Fred Hutchinson Cancer Research Center found that fatal car crashes increase by about 6 percent in the days immediately after the spring clock change.
Experts say the underlying issue is the disruption of the body’s circadian rhythm, the internal biological clock that regulates sleep and wake cycles.
Why Sleep Disruption Happens
Scientists say exposure to natural sunlight plays a crucial role in regulating the body’s internal clock. When Daylight saving time begins, people are exposed to more evening light and less morning light.This shift can make it harder for individuals to fall asleep at their usual bedtime, particularly in the first few days after the clocks change.
Sleep experts explain that the body typically releases melatonin, the hormone responsible for making people feel sleepy, when darkness falls. When sunset occurs later due to the clock adjustment, this natural process may be delayed.
The resulting sleep loss can lead to fatigue, reduced concentration and irritability.
Children who must wake up early for school and shift workers are among the groups most affected by the schedule change. People living on the western edges of time zones may also experience stronger disruptions because sunrise occurs later in the morning.
Why Daylight Saving Time Still Exists
Despite health concerns and growing public debate, efforts to permanently change or eliminate Daylight saving time have faced political challenges.Over the past decade, several lawmakers have introduced proposals to make daylight saving time permanent or eliminate the seasonal clock change altogether. However, none of these proposals have successfully passed both chambers of Congress.
One frequently discussed proposal, often referred to as the Sunshine Protection Act, aims to make daylight saving time the permanent national standard.
More recently, another legislative effort known as the Daylight Act of 2026 proposes shifting U.S. time zones forward by 30 minutes and keeping them there year-round.
Political leaders remain divided on the issue. Some argue that longer evening daylight benefits businesses and outdoor activities, while others emphasize the health concerns raised by medical researchers.
Public opinion is also split. Some Americans prefer brighter evenings, while others favor more daylight in the early morning hours.
As a result, the clock-changing system has remained in place.
Tips for Adjusting to the Time Change
Sleep specialists recommend several strategies to help ease the transition to Daylight saving time.Gradually shifting bedtime earlier by 15 to 20 minutes in the days leading up to the change may help the body adjust more smoothly. Setting clocks forward on Saturday evening rather than waiting until Sunday morning can also reduce confusion.
Experts also suggest spending time outdoors in natural sunlight on the first morning after the change, as early light exposure helps reset the body’s internal clock.
