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 raises the risk of heart attacks and fatal car crashes, but living with DST during summer months may actually lower overall death rates and traffic accidents.
We just went through daylight saving time 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 every major study on DST and health 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 of us have heard the messaging that daylight saving time is bad for our 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 clearly comes with real, measurable health risks, particularly for heart attacks and traffic accidents in the days that follow. However, the summer months spent in DST may actually come with benefits, including lower overall death rates and fewer traffic accidents. What I take away from this is that the transition itself is the 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 also found an increase in fatal traffic accidents after the spring shift, with four rated as high quality.
But the review also uncovered benefits that rarely make the headlines. Five high-quality studies 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, two high-quality studies found fewer traffic accidents during DST, while three studies 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 seven 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,” especially on Monday morning, when the data shows the greatest spike in fatal accidents.
- 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
- Warm Shower or Bath Before Bedtime Improves Sleep: Meta-Analysis Evidence
- 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 our 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 strongest evidence points to the transitions themselves being the most harmful part of the current system.
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 lack of strong evidence may reflect the difficulty of studying these effects at a population level rather than a true absence of impact. 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 poses real, well-documented risks to your heart and your safety on the road. But the summer months spent in DST appear to come with genuine benefits, including lower overall mortality. The strongest message from the data is that the abrupt transitions are the most dangerous part, 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.
