Most Americans will set their clocks back on Nov. 2 for daylight saving time, but a new study suggests the two annual time changes may actually be harmful to our health.

A recent study conducted by Stanford Medicine has found that the practice of shifting clocks for daylight saving time may contribute to increased rates of heart attacks, strokes, and obesity. The researchers suggest that adopting a permanent standard time could help mitigate these health risks, potentially preventing hundreds of thousands of cases of stroke and millions of cases of obesity each year.

The study examined data across the 48 contiguous U.S. states, considering factors such as geographical location and light exposure. The findings indicate that receiving light earlier in the day, as would occur with permanent standard time, supports a healthier circadian rhythm. While the individual risk from a single time change is small, the collective impact on the population is significant.

Seasonal time shifts may be harmful to your health, study finds

Now, most Americans will set their clocks back on November 2nd for daylight saving time, but a new study suggests those two annual time changes, they may actually be harmful to our health. Researchers at Stanford Medicine say that falling back and springing forward may lead to an increase in heart attacks, obesity, and strokes. The study says shifting to a permanent standard time could help mitigate those risks. The researchers estimate that making the switch could prevent about 300,000 cases of strokes per year. It could also result in more than 2 million fewer cases of obesity. Can you believe that? Jamie Zeitzer is the co-author of that study. He is the co-director also of the Stanford University Center for Sleep and Circadian Sciences. Thanks for joining us here to talk about this. I mean, these numbers really are eye-popping. What is the connection between time changes and these health risks? Basically, the time changes are just assigning when you're getting the light. We're not changing how much light you're actually getting, it's just when you're getting it. And when you're in permanent standard time, you're getting light earlier in the day, and that's actually better for your circadian system. It makes a more robust circadian clock, which is this 24-hour clock that you have in your brain that's so important for health. And you bring up locations. I know that you and your colleagues looked at how locations and where you are play a role in all of this. Can you elaborate more on what you found on that perspective? Sure. So we looked at the 48 contiguous states and looked at each county level. So how much light people are getting in each county, where the county is located in terms of north-south, when the light is occurring. So depending on where you are in the country, you're going to be getting light earlier or later. So if you're on the eastern part of a time zone, you're going to be getting light much earlier. If you're on the western part, you're going to be getting it much later. If you're further north, your days are going to be shorter in the wintertime compared to what it's like in the south. So it's complex in terms of how much light you're getting, when you're getting it and where the population is actually living, and also how healthy the population, because none of this isn't going to make you get obese and it's not going to make you have a stroke. This is all going to contribute. It's kind of like you're getting a lottery ticket when you're doing this. So it's basically going to change how much the likelihood that you're going to actually get one of these problems. Yeah, Jamie, I would just say that as someone who has to go around and change all the clocks on my microwave and the stovetop and everything, I'm against it just because it feels like you shouldn't be walking out into darkness at the end of your day, finishing a normal work day. That said, I know right now Hawaii and Arizona are the only two states that don't make the time switch. So what kind of advice do you have for Americans who, like me, have trouble coping with these changes? Yeah, so a lot of people don't have any problem. It's an hour shift. In the spring, that's when it's the most dangerous in terms of a singular event. You're losing an hour of sleep in the spring. It's changing an hour. The shift is not a huge medical risk to any individual. You see it because you have 350 million Americans doing it on the same day. And so what we're really looking at here is what happens if you just make it permanent? What changes there? So, again, if you're looking at how do people adapt to this? Again, you can change your sleep schedule. You can get up earlier. You can get up a little later. It's really kind of making sure that whatever sleep schedule you're picking is going to be healthy for you. And getting light earlier is definitely going to be something that's healthier. I'll take that. Jamie Zeitzer, thank you so much for joining us. Thank you.

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