Time change: How harmful is it for our body? Here’s what new studies say

According to a study published in the Proceedings of the National Academy of Sciences, maintaining permanent standard winter time is more beneficial for the human body compared to both permanent daylight saving time and the current seasonal clock-change system.

The study was conducted by Dr. Jamie Zeitzer, a professor of psychiatry, and Lara Weed, a biomedical engineering PhD.

They analyzed light exposure in every county across the 48 contiguous U.S. states and compared the data with health information from federal databases.

Using mathematical models, the researchers assessed the so-called “circadian load,” an indicator of the stress the body’s biological clock experiences under three different time scenarios.

The conclusion was clear: standard winter time causes the least stress on the body and, therefore, represents the healthiest option for the public.

“Our body is regulated by the sun.”

Dr. Karin Johnson, a neurologist at the University of Massachusetts and member of the American Academy of Sleep Medicine, emphasizes the importance of sunlight for the body’s internal rhythms. According to her: “Our biological clock is slightly longer than 24 hours, so we need daily cues—like sunlight—to stay in sync. The more we align with solar time, the healthier we are: sleep improves, brain function is better, and overall well-being increases.”

Dr. Johnson testified before the U.S. Senate last April, advocating permanent standard winter time as the healthiest and most natural option.

However, in the U.S. Congress there are efforts to implement permanent daylight saving time through the Sunshine Protection Act, a bill supported, among others, by former President Donald Trump.

Although the issue is not strongly partisan, politicians like Senator Ted Cruz acknowledge that there are strong arguments on both sides.

Daylight saving time is preferred by many because it provides more light in the evenings during summer. But Dr. Johnson counters:

“People think they want daylight saving time, but what they really want is summer. With standard winter time, summer nights will still be long.”

She adds that a lack of morning light in winter—if permanent daylight saving time is implemented—could negatively affect health, sleep, and daily functioning, especially for children and those who start work early in the morning.

What does public opinion say?

According to a 2024 Gallup poll:

48% of Americans support permanent standard winter time

24% support permanent daylight saving time

19% want to keep the current system with two annual clock changes

In contrast, a 2023 YouGov survey showed:

50% of respondents who wanted to end the clock changes preferred permanent daylight saving time

31% supported permanent standard winter time

Pros and cons

Supporters of permanent daylight saving time highlight potential benefits such as:

Reduction in seasonal depression

Energy savings

Fewer traffic accidents

However, the American Academy of Sleep Medicine (AASM) lists permanent daylight saving time as the most harmful of the three options.

Although Dr. Zeitzer’s study acknowledges that daylight saving time is less harmful than a permanent double-switch system, it adds:

“Circadian rhythms are only part of the story. We also need to consider behaviors: Do people exercise more when there is morning light? Do children walk less to school when it is dark? Are there economic benefits for vulnerable communities? The impact varies greatly from one region to another.”

For Dr. Johnson, the path is clear: It is a slow and difficult process, but with studies like this, we can gradually shift public opinion toward permanent standard winter time. People are desperate to stop the clock changes.

“KORÇA BOOM”