Daylight Saving Time Is Actually a Nightmare for Your Body and Here’s the Proof
Twice a year, Americans reset the clocks in a practice that has outlived its original purpose. An hour is added in spring and taken back in fall. This routine is carried out as harmless, but research shows otherwise. It feels like a harmless shuffle of hours, the kind of quirk you accept like paying for baggage at the airport. But under the surface, those little clock flips have consequences on your body in surprising and measurable ways.
The evidence goes beyond grogginess at the start of the week. Hospitals record increases in medical emergencies, accident rates climb, and recovery from the disruption can stretch well past a few days. Physicians and scientists argue that the ritual is misaligned with human biology, and the consensus is growing that abandoning it would improve public health.
It was originally a wartime policy to save fuel, but has become a modern headache that fails to line up with how our bodies work. The evidence keeps piling up, and the story it tells is that most of us would be healthier if the whole practice ended.
The Monday Spike Nobody Wants
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Every spring, hospitals brace for a very specific trend. On the Monday after clocks jump forward, studies show a 24 percent rise in heart attack visits across the U.S. Researchers in Finland also tracked an 8 percent bump in ischemic strokes in the two days that follow the spring change. Why?
That missing hour disrupts sleep, throws off blood pressure patterns, and puts stress on already vulnerable systems. By fall, the reverse happens: heart attack cases dip when people get that bonus hour of rest. It highlights how sensitive the human body is to even the smallest changes in time.
The ripple effect doesn’t stop there. Car accident data from over 20 years shows a 6 percent increase in crashes the week after daylight saving time kicks in.Workplaces also feel the strain. A 23-year study of miners found more injuries, and those injuries tended to be more serious on the Monday after the shift. Even outside emergency rooms, fatigue and reduced productivity persist well after the clocks are set.
Your Body Clock Refuses to Adjust
The science here comes down to circadian timing, the body’s natural system for keeping schedules. It runs on cues from sunlight, not wall clocks. When mornings stay dark and evenings stretch out artificially, hormones that regulate sleep, appetite, and metabolism fall out of sync.
Experts at Stanford and Northwestern have shown that this “circadian misalignment” raises risks for obesity, stroke, heart disease, diabetes, depression, and more. One modeling study estimated that staying with permanent standard time could prevent 2.6 million cases of obesity and 300,000 strokes in the U.S. each year.
Professional groups like the American Academy of Sleep Medicine and more than 20 other health organizations have called for the U.S. to ditch the time switches altogether and adopt standard time year-round. It’s not simply preference—it’s biology. Early morning light keeps the internal clock steady, keeps cortisol and melatonin on track, and supports healthier sleep and wake cycles. Permanent daylight saving, on the other hand, means darker mornings and more disruption for most people.
History Shows People Hated It Too
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Permanent daylight saving was tested in the United States during the 1970s energy crisis, and the reaction was swift. Parents complained about children walking to school before sunrise, accidents were reported, and approval ratings collapsed. Congress reversed the policy within months. Recent opinion surveys show little change in sentiment. A Gallup poll in 2025 found that nearly half of Americans preferred permanent standard time, while only a quarter supported permanent daylight saving. Fewer than one in five wanted to keep shifting the clock.
The rest of the world has largely abandoned the practice. By 2024, 176 nations no longer observed daylight saving. In the U.S., Hawaii, Arizona, and several territories already stay on standard time year-round, showing it is possible to function without seasonal changes. Supporters of daylight saving argue that longer evenings reduce crime, lift retail sales, and give people more time outside. Research backs some of those claims. Robbery rates have dropped by more than a quarter in the evenings after the spring change, and industries such as golf and barbecue report hundreds of millions in added revenue.
Those gains come with costs. Studies estimate that the United States loses more than $670 million each year in accidents, hospitalizations, and reduced productivity tied to the clock change. Economists have also calculated that the simple act of resetting clocks wastes $1.7 billion in opportunity costs. The balance of evidence shows that the drawbacks outweigh the benefits.