Twice a year, millions of Americans experience a peculiar ritual that has them adjusting their clocks, complaining about lost sleep, and wondering why we still do this to ourselves. Whether it’s “springing forward” in March or “falling back” in November, the biannual dance with daylight saving time (DST) has become a uniquely American annoyance—backed by a growing body of scientific evidence that suggests it’s also doing more harm than good to our health.
The Health Clock Is Ticking
A groundbreaking new study from Stanford Medicine researchers has added significant weight to arguments against the current time-shifting system. Published in 2025, the study compared three scenarios: our current biannual time changes, permanent daylight saving time, and permanent standard time. The conclusion? Our current system is the “worst choice” for American health.
The findings are compelling. According to the Stanford analysis, switching to permanent standard time could prevent approximately 220,000 stroke cases and 1.7 million obesity cases annually. While these numbers may seem modest in percentage terms (0.04% for stroke and 0.51% for obesity), they represent real people whose lives could be improved or saved by a policy change.
Why Standard Time Outperforms Its Alternatives
The study indicates that while both permanent standard time and permanent daylight saving time would be improvements over our current system, standard time edges out as the healthiest option. But why?
The answer lies in our circadian rhythms—the biological processes that regulate our sleep-wake cycles, hormone production, and even digestion. Permanent standard time better aligns with natural light patterns, particularly the crucial morning light that helps synchronize our internal clocks.
When we shift to daylight saving time in the spring, we essentially force ourselves to live in a time zone where the sun rises later according to our clocks. This misalignment, sometimes called “social jet lag,” can disrupt sleep patterns and has been linked to various health issues including increased risk of heart disease, diabetes, and even certain cancers.
Consensus Among Medical Experts
The Stanford findings aren’t a lone voice in the wilderness. Several major medical organizations have come out strongly in favor of permanent standard time:
- The American Academy of Sleep Medicine updated its position in October 2023 to support replacing DST with permanent standard time
- The National Sleep Foundation has issued a position statement supporting permanent standard time
- The American Medical Association has also endorsed the move away from biannual time changes
These endorsements aren’t based on whimsy or politics. The health effects of time changes are measurable and well-documented. Studies have consistently shown increases in heart attacks, strokes, and traffic accidents in the days immediately following the spring time change. The fall change, while seemingly less disruptive, still causes measurable disturbances to sleep patterns and workplace productivity.
A Brief History of Daylight Saving Time in America
Daylight saving time in the United States has a surprisingly complex history. First implemented during World War I as an energy conservation measure, DST became a patchwork of local and state choices until the Uniform Time Act of 1966 established a more standardized system. However, the law still allows individual states to opt out (Arizona and Hawaii notably do).
Despite its long history, the original rationales for DST—namely energy conservation—have been largely debunked in the modern era. With our increased reliance on air conditioning, some studies suggest that DST may actually increase energy consumption in certain regions.
Public Sentiment Matches Scientific Consensus
Beyond the medical community, public opinion appears to be shifting as well. A Gallup poll conducted in January 2025 found that only 40% of Americans favor continuing with daylight saving time, while 6% remained uncertain. More tellingly, a Stetson University survey from March 2025 showed that 54% of Americans support eliminating the biannual clock changes entirely in favor of a permanent system—though respondents didn’t distinguish significantly between permanent standard time and permanent daylight saving time.
This disconnect between public preference and medical recommendation may stem from a general misunderstanding of what “permanent daylight saving time” would actually mean. Many people associate the term with more evening light for activities like sports or shopping, not realizing that it would mean later sunrises—particularly problematic during winter months when children might wait for school buses in darkness.
Legislative Momentum
The combination of medical evidence and public sentiment has already begun to influence policymaking. The Sunshine Protection Act, which would make daylight saving time permanent nationwide, has gained traction in recent years, passing the Senate in 2022 (though it has stalled in the House). However, medical organizations warn that this approach may solve one problem while creating another.
The disconnect between what legislators are proposing and what medical experts recommend highlights the challenge of translating scientific consensus into policy. It’s one thing for Americans to be tired of changing clocks twice a year; it’s another to ensure that the permanent solution actually benefits public health.
The Path Forward
So where does this leave us? The biannual ritual of changing clocks appears increasingly anachronistic in a modern society that already struggles with sleep deprivation and chronic health conditions. While we may never agree on whether having more evening light is worth the disruption, the health evidence clearly points toward adopting a permanent time system.
As the Stanford study demonstrates, even small improvements in population health can translate to significant benefits when applied to a nation of over 330 million people. The question isn’t whether we should stop changing our clocks twice a year—that much is clear—but rather which permanent system will do the least harm and provide the greatest benefit.
Until policymakers listen to both the medical evidence and public sentiment, Americans will continue their ritual dance with time changes, never quite certain if they’re gaining more daylight or sacrificing their health in the process.
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