The Next Time Change Is Coming. Scientists Warn: It Harms Your Health

We Will Soon Change the Clocks. Scientists’ Warnings

This year, the change to Standard Time (winter time) will occur from October 25th to October 26th. We will move the clocks back from 3:00 AM to 2:00 AM. Although we gain an hour of sleep, a growing body of research shows this benefit is merely an illusion. Why? Because time changes negatively impact our health and well-being. How exactly?

Stanford Scientists: Three Scenarios, One Conclusion

To find out, researchers at Stanford University conducted a specific study. They compared three scenarios: permanent Standard Time, permanent Daylight Saving Time, and two annual changes—in spring and autumn. The study aimed to show which option posed the least harm to the body. But this was, of course, just the beginning.

How Light Affects Our Biological Clock

Over a year, the scientists analyzed how people functioned in natural conditions—at work, at home, and outdoors. They investigated how light exposure affects the human biological clock. They also utilized data from the Centers for Disease Control and Prevention, which allowed them to accurately assess how the change in light exposure throughout the day impacts health and well-being.

The results are troubling.

Why Does the Time Change Harm Your Health?

Research published in the prestigious journal PNAS leaves no doubt—the current system of two annual time changes represents the greatest burden on the body. These abrupt transitions from DST to Standard Time and vice versa most severely disrupt our circadian rhythm, causing a so-called “mini jet lag.”

Permanent Standard Time – The Best for Health

Scientists indicate that permanent Standard Time is the best solution for health. Why precisely? Because it is most closely aligned with natural daylight, facilitates falling asleep, improves sleep quality, and supports body regeneration. This is the rhythm with which the human biological clock cooperates best.

Morning light proved crucial. Permanent Standard Time means that right after waking up, we access more natural light, which wakes up the body and regulates the circadian rhythm. Conversely, in the evening, when it gets dark earlier, it becomes easier to wind down and fall asleep.

Time Change and Health Benefits

The study also showed that most people tested are “night owls”—individuals who naturally function better later in the day. Standard Time is simply closer to their biological rhythm, which translates into concrete benefits:

• Better sleep,
• Greater concentration,
• Lower risk of health problems.

Experts have no doubt—permanent Standard Time presents a real benefit to public health. If it applied year-round, the majority of people’s circadian rhythms would be more stable, and the body would function naturally, without artificial disruption.

Why does this matter so much? According to the scientists’ analysis, permanent Standard Time could prevent up to 300,000 strokes annually. That’s not all—2.6 million fewer people would struggle with obesity and metabolic issues.

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Who Loses the Most from the Time Change?

Only about 15 percent of people are “morning larks”—individuals who naturally wake up early and have the most energy in the morning. Daylight Saving Time might indeed be more beneficial for them. It is worth noting that Stanford researchers indicated that even prolonged access to evening light can slightly reduce the risk of strokes and metabolic problems.

This is only part of the truth, however. A stroke still occurs globally every 40 seconds, and 2 in 5 adult Americans struggle with obesity. Both problems are strongly linked to circadian rhythm disorders. Therefore, the key question remains: if DST has certain advantages, why do experts still point to Standard Time as healthier?

The Health Effects of Daylight Saving Time: DST Does Not Save the Situation

Although Daylight Saving Time has some advantages, scientists emphasize that it performs significantly worse compared to Standard Time. If it applied year-round, it would indeed bring some health benefits—the number of strokes would fall by about 220,000 annually, and obesity cases would be fewer by 1.7 million. The problem is that this is still a much worse result than that of permanent Standard Time, which yields nearly half the health benefits more. The difference is clear—and hard to ignore.

The Last Time Change? Scientists Appeal

The impact of moving the clocks on physical and mental well-being is much greater than previously thought for years. Research clearly shows that permanent Standard Time aligns most closely with the natural human rhythm, and is therefore most beneficial for health. It means fewer sleep disturbances, fewer metabolic ailments, and a lower risk of cardiovascular diseases. No wonder a growing number of scientists appeal: the upcoming time change should be the last.

Read this article in Polish: Nadchodzi kolejna zmiana czasu. Naukowcy ostrzegają: szkodzi zdrowiu