The Naturalness of the Seasonal Time Change: Researchers Question Basis of Modern Criticism
taylorvich writes:
https://medicalxpress.com/news/2025-03-naturalness-seasonal-basis-modern-criticism.html
What is the best time to start the day in view of the variation in when the sun rises? This is the problem analyzed by Jorge Mira Perez and Jose Maria Martin-Olalla, lecturers at the University of Santiago de Compostela (USC) and the University of Seville (US), in a study that has just been published in the journal Royal Society Open Science. In it, they analyze the physiological and social foundations of the practice of seasonal time change and review its impact on health.
The study takes as an example the cities of Bogota and New York, which are located on the same meridian but at different latitudes, to point out that in winter the sunrise is delayed by an hour-and-a-half in the latter city. "This delays life in New York during the winter, but in spring the delay in sunrise has disappeared and activity can start earlier. Putting the clocks forward in spring facilitates this adaptation," says Mira.
The study includes several current and past examples of societies with delayed activity in winter and earlier activity in summer, in line with the synchronizing role of morning light for our bodies. "Modern societies have several synchronization mechanisms. For example, the use of a standard time in a large region, or the use of pre-set schedules. Time shifting is another synchronizing mechanism, which adapts human activity to the corresponding season," says Martin-Olalla. The authors suggest that the first weekend in April and the first weekend in October would be the most appropriate time for the clocks to change.
The study reviews the impact of the seasonal time change on human health, considering two types of effects: those associated with the change itself, and those associated with the period during which daylight-saving time is in effect. In the first case, the authors point out that published studies have not analyzed the problem epidemiologically and that the evidence suggests that the impact is very weak.
"A very comprehensive study in the United States reports a 5% increase in traffic accidents in the week following the clocks going forward in spring but overlooks the fact that from one year to the next, weekly traffic accidents fluctuate by 15%. Changing the clocks has an impact, but it is very weak compared to the other factors influencing the problem," Mira points out.
"Changing the clocks has worked for a hundred years without serious disruption. The problem is that in recent years it has been associated only with energy saving when, in fact, it is a natural adaptation mechanism," says Martin-Olalla.
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