Daylight Saving Time Doesn’t Boost Daily Steps, Study Finds

Daylight saving time (DST) is often promoted as a way to encourage more physical activity by providing longer evening daylight. However, recent research challenges this assumption, showing that the time change does not lead to increased daily movement.

Study Findings on Physical Activity

A study conducted by researchers at Duke University analyzed step-count data from wearable devices to assess whether DST influences physical activity levels. The research utilized data from the All of Us Research Program, a large-scale health initiative supported by the National Institutes of Health. By comparing regions that observe DST with those that do not—such as Arizona versus neighboring states like Colorado, New Mexico, and Utah—the study found no significant increase in daily steps associated with the time shift.

The researchers emphasized that their approach relied on objective measurements from wearables rather than self-reported surveys, which can be subject to bias. This method provided a clear record of actual movement patterns before and after clock changes.

Broader Health Implications of Daylight Saving Time

While the Duke study focused on physical activity, other research has examined the broader health effects of DST. A study from Stanford Medicine evaluated three different time policies—permanent standard time, permanent daylight saving time, and the current biannual switching—and their impact on circadian rhythms and health outcomes. The researchers found that either permanent standard time or permanent daylight saving time would be healthier than the current practice of switching clocks twice a year. Specifically, modeling indicated that permanent standard time could result in approximately 300,000 fewer people experiencing a stroke and 2.6 million fewer cases of obesity nationwide.

The Stanford team concluded that maintaining a consistent time year-round—whether standard or daylight saving—would better align with the body’s natural circadian rhythms, which regulate essential physiological processes such as sleep, hormone release, and metabolism. Disruptions caused by biannual clock changes have been linked to increased risks of heart attacks, stroke, and other health issues.

Understanding the Purpose of Daylight Saving Time

Daylight saving time was originally implemented to make better use of daylight during longer days in the summer months. The practice stems from the Earth’s axial tilt of approximately 23.4 degrees, which causes seasonal variations in daylight hours. As the Earth orbits the Sun, this tilt results in longer days in summer and shorter days in winter for each hemisphere.

Despite the intention to conserve energy and promote outdoor activity, modern evaluations suggest that the energy savings from DST are minimal, and the disruption to circadian rhythms may outweigh any potential benefits. The practice remains controversial, with ongoing debate about its effects on health, safety, and energy consumption.

Conclusion

Current evidence indicates that daylight saving time does not increase daily physical activity, as measured by step count. The biannual clock changes associated with DST may pose health risks due to circadian disruption. Experts suggest that adopting a permanent time standard—either permanent standard time or permanent daylight saving time—could mitigate these risks and better support public health. As research continues, policymakers may require to reconsider the long-term value of daylight saving time in light of its limited benefits and potential harms.