Every year, as Americans prepare to “spring forward” for daylight saving time (DST), millions experience the familiar struggle of losing an hour of sleep. While the time change may seem like a minor inconvenience, research suggests that daylight saving time is more than just an annoyance—it poses significant risks to health, productivity, and safety.
Scientists and sleep experts have been sounding the alarm for years, warning that shifting the clocks ahead each March disrupts our natural sleep-wake cycles, increasing the likelihood of heart attacks, strokes, car accidents, and even mental health issues. Despite these concerns, policymakers remain divided on whether DST should be abolished, made permanent, or left as it is.
The Hidden Health Costs of Daylight Saving Time
Many people assume that adjusting the clocks by just one hour wouldn’t have a major impact, but sleep specialists strongly disagree. Dr. Beth Ann Malow, a professor of neurology and pediatrics at Vanderbilt University Medical Center, has studied the effects of DST extensively. She warns that “springing ahead” each March is far from harmless.
“Based on an extensive body of research, my colleagues and I believe that the science establishing these links is strong and that the evidence makes a good case for adopting permanent standard time nationwide,” Malow wrote in a commentary for JAMA Neurology.
What exactly happens to the body when daylight saving time begins? The key problem lies in the disruption of our circadian rhythm, the internal biological clock that regulates sleep, hormone production, metabolism, and overall health.
According to Dr. Carla Finkielstein, a professor at Virginia Tech’s Fralin Biomedical Research Institute, “Daylight saving time messes with our biological clocks by reducing morning sunlight exposure, which pushes our sleep schedules later and can have negative effects on health.”
This disruption leads to a wide range of health problems, including:
- Increased risk of heart attacks – Research has found that heart attacks spike by nearly 24% in the days following the shift to daylight saving time. Sleep deprivation increases stress on the cardiovascular system, raising the risk of fatal heart events.
- Higher rates of stroke – A study published in Sleep Medicine found that stroke rates rise significantly in the first two days after the springtime clock change.
- Greater likelihood of mental health struggles – Suicide rates tend to rise in the weeks following the switch to daylight saving time, particularly among individuals vulnerable to depression. Dr. Malow notes that “exposure to light later into the evening delays the brain’s release of melatonin, the hormone that promotes drowsiness. This can interfere with sleep and cause us to sleep less overall.”
- More car accidents – Studies show that drowsy driving spikes after the time change, increasing the risk of fatal crashes. A study by the University of Colorado found a 6% increase in fatal car crashes in the week following the start of daylight saving time.
Who’s Pushing to Eliminate Daylight Saving Time?
A growing number of sleep experts, medical professionals, and safety organizations have called for an end to daylight saving time, arguing that the evidence overwhelmingly supports permanent standard time instead.
The American Academy of Sleep Medicine (AASM) has issued a strong recommendation against DST, stating:
“Standard time most closely approximates natural light, with the sun directly overhead at or near noon. In contrast, during daylight saving time, the natural light is shifted unnaturally by one hour later.”
Similarly, the National Safety Council and Centers for Disease Control and Prevention (CDC) have voiced opposition to DST, citing its links to increased workplace injuries, sleep disorders, and chronic health problems.
Other experts echo these concerns. Dr. Alaina Tiani, a clinical health psychologist at the Cleveland Clinic’s Sleep Disorder Center, states:
“Permanent standard time is undeniably the best option for our health—if you believe in science.”
The opposition to DST isn’t just theoretical; real-world examples back up these concerns. Countries that have tried permanent daylight saving time, including the United States (1974), Russia (2011), the United Kingdom (1971), and Portugal (1996), ultimately reversed the decision after widespread public dissatisfaction, increased morning car accidents, and major disruptions to daily life.
What About the Benefits of Daylight Saving Time?
Despite the strong case against DST, some argue that keeping later daylight hours has its advantages.
Supporters of permanent daylight saving time, such as former U.S. Senator Marco Rubio, claim that more daylight in the evening encourages outdoor activities, reduces crime, and benefits businesses. His proposed Sunshine Protection Act aims to make daylight saving time permanent across the country.
Some studies suggest that longer daylight hours could slightly reduce crime rates since criminals are less likely to operate in well-lit conditions. Retail stores and restaurants may also benefit from increased foot traffic during longer evening daylight hours.
However, many scientists argue that these benefits are marginal compared to the public health risks. Dr. Malow and her colleagues point out that while crime may drop slightly, the overall impact is minimal compared to the documented rise in heart attacks, strokes, and car accidents linked to DST.
The Impact on Teens: Sleep Deprivation and Early School Start Times
Teenagers are particularly vulnerable to the negative effects of daylight saving time. More than 80% of U.S. middle and high schools start before 8:30 a.m., forcing teens to wake up before their biological clocks are ready.
During puberty, the natural circadian rhythm shifts, making it difficult for teenagers to fall asleep before 11 p.m. When daylight saving time pushes sunrise later, teens are forced to wake up in complete darkness—making an already bad situation worse.
The consequences of teen sleep deprivation include:
- Lower grades and declining academic performance
- Increased risk of depression, anxiety, and suicide
- More car crashes caused by drowsy teenage drivers
- Higher likelihood of engaging in risky behaviors, including drug and alcohol use
Research suggests that delaying school start times to 8:30 a.m. or later could boost the economy by $8.6 billion within two years, largely due to higher graduation rates and improved academic performance.
The “Western Edge” Effect: How Geography Plays a Role
Not all Americans experience daylight saving time the same way. Studies show that people living on the western edge of a time zone suffer worse health outcomes because their morning light exposure is delayed even further.
According to one study, residents on the western edge of a time zone have:
- Higher rates of obesity, diabetes, and heart disease
- Increased risk of breast cancer
- Lower per capita income and higher healthcare costs
Scientists believe these negative health effects stem from chronic circadian misalignment—a constant disconnect between the body’s internal clock and the actual sunrise/sunset times.
What’s the Best Solution?
Given the growing body of research, sleep experts overwhelmingly agree that the U.S. should adopt permanent standard time rather than daylight saving time. This would ensure that morning light exposure is maximized, helping to regulate the body’s sleep-wake cycles and prevent long-term health consequences.
Several states, including Arizona and Hawaii, have already opted out of daylight saving time, remaining on standard time year-round. Now, lawmakers in other states are considering similar measures, and the debate continues at the federal level.
The Bottom Line: Why the U.S. Needs to Rethink Daylight Saving Time
The debate over daylight saving time isn’t just a matter of convenience—it’s a serious public health issue. While some argue that extra evening daylight is beneficial, the scientific evidence strongly favors permanent standard time as the best option for sleep health, mental well-being, and public safety.
With support growing for change and lawmakers reconsidering the tradition, the U.S. may soon wake up to the reality that our clocks should be set to match our biology—not the other way around.
HNZ Editor: In our opinion, the “science” cited by Dr. Tiani and the ASSM is crap. Natural is what has been established previously by culture, time is an artificial construct. We are in favor of permanent Daylight savings time, with more sunlight later in our culturally defined evening.
