Does Daylight Saving Time Actually Harm Your Health?
It depends on which part you are talking about. A massive systematic review of 157 studies from 36 countries found that the spring transition is linked to more heart attacks and fatal car crashes, but living with DST during summer months may actually lower overall death rates and traffic accidents.
Daylight saving time started this past weekend, and if you felt off for a few days, you are not alone. Researchers from institutions across the UK, Germany, and Australia reviewed 157 peer-reviewed studies on DST and health, in English or German, published through June 2025. Their findings, published in the European Journal of Epidemiology, paint a much more nuanced picture than you might expect.
Dr. Kumar’s Take
I think this review is incredibly timely and important. Most people have heard the messaging that daylight saving time is bad for health, and major medical organizations have called for its elimination. But what this comprehensive review reveals is that the picture is far more complex. The spring transition appears to be linked to more heart attacks in the days that follow, and to more fatal traffic accidents in some places, especially the USA. The summer months spent in DST may come with benefits, including lower overall death rates and fewer traffic accidents, but each of those rests on a single study. What I take away from this is that the spring transition is the main problem, not necessarily DST as a concept. And the good news is that there are practical steps you can take to protect yourself during these transition periods.
What the Research Shows
The review found strong evidence that “springing forward” is linked to increased heart attacks. Seventeen studies examined this connection, with six rated as high quality, and the pattern was consistent: the days following the spring time change show a bump in acute myocardial infarction. Sixteen studies looked at fatal traffic accidents, four of them rated high quality, and the evidence points to an increase after the spring shift in some places, especially for fatal crashes in the USA, but not everywhere. The review rated its confidence in the traffic finding as medium.
But the review also uncovered benefits that rarely make the headlines. Five studies, three of them rated high quality, found that crimes involving physical harm actually decrease after the spring transition, likely because of the extra evening daylight. And when comparing summer months spent in DST versus standard time, one high-quality study found fewer traffic accidents during DST, and one high-quality study found lower all-cause mortality.
The fall transition (“falling back”) had its own pattern. The shift was associated with decreased workplace accidents and lower all-cause mortality, but it came with an increase in violent crime. Sleep duration tended to increase after the fall transition, as you might expect from gaining an hour.
Gaps in the Evidence
One surprising finding was how little solid evidence exists for some commonly discussed concerns. Fifteen studies looked at psychiatric outcomes like depression and anxiety around DST transitions, but only one was rated as high quality, and no clear or consistent effects were found. Similarly, only six studies examined circadian rhythm disruption directly, none of which were rated as high quality. So while the biological logic for circadian disruption is sound, the epidemiological evidence is still catching up.
Practical Takeaways
- Start shifting your bedtime 15 to 20 minutes earlier for three to four nights before the spring transition, so your body can adjust gradually instead of losing a full hour at once.
- Get bright morning sunlight in the first 30 minutes after waking during the week following the time change, as light is the strongest signal for resetting your internal clock.
- Avoid caffeine after noon and limit alcohol in the days surrounding the transition, since both can further disrupt your already-shifting sleep patterns.
- Be extra cautious on the roads in the week after “springing forward,” when fatal accidents tend to rise.
- If you have a history of heart problems, pay close attention to how you feel in the days following the spring transition and do not hesitate to seek medical attention for any unusual symptoms.
Related Studies and Research
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- Acute Sleep Loss Impairs Physical Performance: Systematic Review and Meta-Analysis
- Chamomile Tea Improves Sleep Quality in Elderly: Clinical Trial Evidence
- Does High LDL-C Help Elderly People Live Longer? A Review of 19 Studies
FAQs
How long does it take for your body to adjust after daylight saving time?
Most people need about five to seven days to fully adjust to the one-hour shift, though it can vary based on your individual chronotype (whether you are naturally a morning person or a night owl). Evening chronotypes, sometimes called night owls, tend to have a harder time adjusting to the spring transition because their internal clocks are already running later than the social clock demands. During this adjustment period, you may notice increased daytime sleepiness, difficulty concentrating, and changes in appetite. Prioritizing consistent wake times and morning light exposure can help speed the process along.
Is permanent daylight saving time or permanent standard time better for health?
This is one of the most debated questions in sleep science right now. Major sleep organizations like the American Academy of Sleep Medicine have advocated for permanent standard time, arguing that it keeps social clocks more aligned with the sun. However, this review found that living with DST during summer months was associated with lower overall death rates and fewer traffic accidents, suggesting that the answer may not be as simple as “standard time is always better.” A 2025 Stanford analysis estimated that permanent standard time could prevent roughly 300,000 strokes and 2.6 million cases of obesity, but permanent DST also showed meaningful benefits. The clearest harms in this review came in the days after the spring transition.
Does daylight saving time affect mental health?
Despite widespread concern, this review found no clear or consistent evidence linking DST transitions to psychiatric outcomes like depression or anxiety. Fifteen studies examined this question, but only one was rated as high quality. That said, the biological reasoning is plausible, because disrupted sleep and circadian misalignment are known risk factors for mood disorders. The authors read the lack of an effect as consistent with the small or absent effects on sleep and circadian rhythms seen in the studies they reviewed. If you are someone who already manages a mood disorder, it is still wise to be proactive about protecting your sleep routine during transitions.
Bottom Line
This review of 157 studies makes one thing clear: daylight saving time is not the simple villain it is often made out to be. The spring transition appears linked to more heart attacks and, in some places, more fatal crashes. The summer months spent in DST may come with benefits, including lower overall mortality, but that evidence comes from single studies and is still limited. The clearest risks in the data come from the spring transition, which means anything you can do to ease the shift gradually, through sleep hygiene, morning light, and extra caution behind the wheel, is time well spent.
