Why Daylight Saving Time Is Bad Health Risks And Impacts

Every spring and fall, millions of people across the United States and parts of Europe adjust their clocks for daylight saving time (DST). While the practice was originally intended to conserve energy and make better use of daylight, decades of research now show that the biannual time shift carries significant health consequences. The abrupt one-hour change disrupts our internal biological rhythms more than most realize, triggering measurable increases in cardiovascular events, workplace injuries, mood disturbances, and long-term sleep disorders. Despite ongoing debates about abolishing DST, the current system continues to pose a public health risk that deserves serious attention.

The Biological Cost of Time Shifts

Human bodies operate on a circadian rhythm—a 24-hour internal clock regulated by light exposure, hormone production, and environmental cues. This biological system governs everything from sleep-wake cycles to metabolism, immune function, and cognitive performance. When daylight saving time forces a sudden shift in schedule, even by just one hour, it creates what scientists call “social jet lag.”

This misalignment between external time and internal biology can take days or even weeks to resolve. During this adjustment period, melatonin production—the hormone responsible for regulating sleep—is delayed or suppressed, particularly during the spring forward transition when people lose an hour of sleep. Research published in the journal Current Biology found that the human body never fully adapts to DST and instead remains in a state of chronic desynchronization for several days post-transition.

“Losing even one hour of sleep can have profound effects on alertness, reaction time, and overall physiological stability.” — Dr. Beth Ann Malow, Neurologist and Sleep Scientist, Vanderbilt University

Tip: Begin shifting your bedtime by 15 minutes per night in the week leading up to the time change to ease the transition.

Increased Risk of Heart Attacks and Strokes

One of the most alarming findings related to daylight saving time is its association with cardiovascular events. A landmark study conducted by the University of Michigan analyzed hospital data over a six-year period and discovered a 24% increase in acute myocardial infarctions (heart attacks) on the Monday and Tuesday following the spring time change.

The stress placed on the cardiovascular system due to sleep deprivation, elevated cortisol levels, and disrupted autonomic nervous system function appears to be the primary driver. Similarly, a Swedish study published in the New England Journal of Medicine reported a 5% increase in stroke incidence during the first two days after the spring shift. These risks were especially pronounced among individuals over 65 and those with pre-existing health conditions.

Event	Time Period After Spring DST	Risk Increase
Heart Attacks	First 3 days	24%
Ischemic Strokes	First 2 days	5%
Emergency Room Visits (cardiac)	First week	8–12%

Mental Health and Cognitive Impacts

Beyond physical health, DST has been linked to deteriorations in mental well-being. A Danish study tracking psychiatric hospital admissions over 16 years found a notable 11% spike in new cases of depression following the switch to standard time in the fall. Researchers attributed this rise to reduced daylight exposure, which affects serotonin levels and can trigger seasonal affective disorder (SAD).

Cognitive performance also suffers. A University of Colorado study revealed a 6% increase in fatal traffic accidents in the week after the spring time change. This equates to approximately 28 additional U.S. deaths annually—directly tied to drowsy driving and impaired judgment. Workplace productivity declines as well, with studies showing increased errors in high-stakes environments like hospitals and manufacturing plants.

• Sleep fragmentation leads to poor concentration and memory lapses.
• Mood swings and irritability are common during adjustment periods.
• Vulnerable populations, including teens and shift workers, face amplified disruptions.

Real-World Impact: A Nurse’s Experience

Consider Sarah Thompson, a registered nurse working night shifts at a regional hospital in Illinois. For years, she managed her rotating schedule with careful planning—until daylight saving time threw off her routine. In March 2022, after “springing forward,” Sarah struggled to fall asleep before 2 a.m., despite going to bed earlier. By her third night shift that week, she misread a medication dosage, catching the error only after double-checking with a colleague.

“I’ve never made a mistake like that before,” she said in a follow-up interview. “But that week, my brain felt foggy. I was exhausted, and I couldn’t reset my rhythm. It wasn’t just me—several nurses on my unit reported similar issues.” Her experience underscores how seemingly minor time changes can compromise safety in critical professions.

Why Permanent Standard Time Is the Healthier Option

While some advocate for permanent daylight saving time, medical experts overwhelmingly support making standard time permanent instead. Unlike DST, standard time aligns more closely with natural sunlight patterns and the human circadian clock. Morning light exposure is crucial for synchronizing our internal rhythms, yet DST delays sunrise in many regions—meaning children wait for school buses in darkness and office workers miss early daylight entirely.

Dr. Charles Czeisler, a leading sleep researcher at Harvard Medical School, explains: “Morning light is the most powerful signal to reset the human clock. When DST pushes sunrise later, it delays that signal, increasing the risk of circadian misalignment.” Countries like Iceland and Japan, which do not observe DST, report more stable sleep patterns and fewer seasonal health fluctuations.

Step-by-Step: How to Minimize DST Health Risks

1. Start adjusting early: Begin shifting your bedtime and wake time by 15 minutes per day three to four days before the change.
2. Maximize morning light: Spend at least 20–30 minutes outside shortly after waking to help reset your circadian rhythm.
3. Avoid screens before bed: Blue light from phones and tablets suppresses melatonin; stop using devices one hour before sleep.
4. Limit caffeine and alcohol: Both substances can interfere with sleep quality during sensitive transition periods.
5. Be extra cautious: Exercise heightened awareness while driving or operating machinery for at least three days after the shift.

Checklist: Protecting Your Health During DST Transitions

• ✅ Gradually adjust sleep schedule 3–4 days in advance
• ✅ Expose yourself to bright morning light
• ✅ Maintain consistent meal and exercise times
• ✅ Avoid napping longer than 20 minutes
• ✅ Monitor mood and alertness for signs of strain
• ✅ Postpone major decisions or complex tasks if fatigued

Frequently Asked Questions

Does daylight saving time actually save energy?

Modern studies show minimal to no energy savings from DST. A U.S. Department of Energy report found that DST reduces electricity use by less than 0.5% per day. With increased air conditioning usage in extended evening daylight, some regions even see higher energy consumption.

Is the fall time change safer than the spring change?

While gaining an hour of sleep in the fall seems beneficial, the abrupt shift still disrupts circadian rhythms. Additionally, darker mornings increase accident risks, and the reduction in daylight correlates with higher rates of depression and fatigue.

Could eliminating DST improve public health?

Yes. Multiple health organizations—including the American Academy of Sleep Medicine—recommend ending seasonal time changes in favor of permanent standard time. This would provide greater circadian alignment, reduce cardiovascular and mental health risks, and enhance overall safety.

Conclusion: Time for Change

The evidence is clear: daylight saving time poses real and measurable threats to physical health, mental well-being, and public safety. From increased heart attacks to impaired cognitive function, the costs outweigh any outdated notions of daylight efficiency. As individuals, we can take steps to mitigate the impact—but systemic change is needed. Supporting policies that adopt permanent standard time is not just a matter of convenience; it’s a public health imperative. Our bodies thrive on consistency, not artificial time shifts. It’s time to prioritize health over tradition and reconsider whether daylight saving time has a place in the modern world.

💬 Do you think daylight saving time should be abolished? Share your thoughts and experiences with time changes in the comments below.