Study Suggests Permanent Standard Time Could Reduce Health Risks Linked to Circadian Disruption

New research from Stanford University has reignited the debate over daylight saving time, suggesting that eliminating the practice could offer significant health benefits. The study, published in the Proceedings of the National Academy of Sciences, found that maintaining standard time year-round—rather than switching twice a year—could reduce the prevalence of obesity and strokes by minimizing the stress on the body’s circadian rhythms.

The research compared three scenarios: permanent standard time, permanent daylight saving time, and the current system of switching clocks seasonally. Using a mathematical model, scientists analyzed sunlight exposure across the 48 contiguous U.S. states and linked it to federal health data. The findings indicated that standard time imposes the least burden on the body’s natural rhythms, which are closely tied to the sun’s cycle.

Dr. Jamie Zeitzer, a professor of psychiatry and behavioral sciences, emphasized that the body’s rhythms are set by the sun, and disruptions from time changes can lead to sleep issues, digestive problems, and other health concerns. “Our body rhythms basically get set by the sun,” he says, “and we need daily cues to stay on track. Otherwise, our rhythms get delayed.”

While some argue that permanent daylight saving time could extend evening light and potentially reduce seasonal depression, advocates for standard time, including Dr. Karin Johnson of the University of Massachusetts, argue that aligning with the sun’s natural cycle is healthier for both the body and mind. “The more we can stay aligned with the sun time,” she says, “the healthier it is for our body, the better our brain functions, the better our sleep.”

The American Academy of Sleep Medicine (AASM), American Academy of Neurology, and the National Safety Council all support the shift to permanent standard time, citing the potential for improved health outcomes. However, the issue remains politically contentious, with former President Donald Trump and some members of Congress advocating for the permanent adoption of daylight saving time.

According to a recent Gallup poll, 48% of Americans support permanent standard time, while 24% back permanent daylight saving time and 19% prefer the current system. However, earlier polling from YouGov in 2023 showed a more balanced view, with 50% supporting permanent daylight saving and 31% favoring standard time.

Advocates of permanent daylight saving time have suggested it could help reduce vehicle crashes, save energy, and alleviate seasonal depression. However, Dr. Zeitzer cautions that circadian rhythms are just one part of the equation. “Do people exercise more if there’s more light in the morning? Are fewer kids biking to school because it’s too dark in the morning? Are there better economic outputs that could help economically marginalized individuals?” he asks. “There are lots of things that could happen if you move where that hour of light is happening, and frankly, it might be very different in different parts of the country.”

As the debate continues, health experts hope that studies like this will help shift public opinion. “It’s a long, slow process,” says Dr. Johnson, “but I think getting the word out with studies like this can hopefully shift that needle toward permanent standard time. Because people are desperate to end the time change.”