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Permanent daylight saving time could have health downsides


The Senate has passed a bill that would end the chore of resetting our clocks twice a year. The Sunshine Protection Act would make daylight saving time permanent year-round beginning in the fall of 2023. The bill now goes to the House. Its chances there are unclear. Meanwhile, the American Academy of Sleep Medicine warns that it could harm public health.

Dr. Karin Johnson is an associate professor of neurology at UMass Chan Medical School Baystate and medical director of the Baystate Regional Sleep Medicine Program. She joins us now. Thanks for being with us.

KARIN JOHNSON: Thank you for having me.

SIMON: People don't like switching clocks back and forth. And, you know, the senators that spoke in favor of this bill talked about how it disrupts the sleep cycles of children and darker afternoons. What do you say to all that?

JOHNSON: The majority of people do support ending clock change. Not only do people feel worse, as we're feeling this week, but there is increased health risk, things like increased strokes and heart attacks, as well as car accidents that occur in that week after time change, especially in the springtime.

SIMON: But you have some caution on this, too, don't you?

JOHNSON: So there's two ways to end clock change. One is to go to permanent daylight saving time, and one goes to permanent standard time. And so the scientific and medical community really feel it's very important for us to go to permanent standard time, which is much more aligned with the sun in the sky and so better for our overall health and well-being.

SIMON: Well, explain how that works out to us, if you could.

JOHNSON: So we all have body clocks, and they align to the sun. And studies have shown that even after switching to daylight saving time, our hormones stay with the sun. And so we end up living our social life by a clock time, when we go to work and school, but our body's clock is on that sun times still. And so that leads to at least about an hour of misalignment. But parts of the country, especially in the western parts of time zone, are misaligned by about 2 hours. And so that, again, affects things like our health. It affects how we sleep. There's more sleep deprivation and poor quality sleep when you're more misaligned. And that in itself has effects that last the whole time we're on daylight saving time.

SIMON: And how could we pay for that in terms of our health?

JOHNSON: So some of the research we have the best data on is increase in obesity. We also have a lot of good data now from multiple studies about cancer. And so some of these studies look at just the effect of where we are in the time zone and places in the country that are more aligned by an hour, similar to time change, have about a 12% increased risk in cancer. And certain types of cancer like liver cancer are even higher than that.

SIMON: The Senate approved the bill by an expedited process. As you've probably read, no one objected. There was no debate, and BuzzFeed has since reported some senators maybe didn't know what was going on. At least one would have objected if they had. I know you don't want to diagnose from a distance, but what do you figure? They were sleep-deprived?

JOHNSON: So there are some strong lobbies that are for permanent daylight saving time. And so, you know, a lot of people probably said, hey, it's popular to end time change. No one's going to really think about which way to go, so let's push it on through.

SIMON: Dr. Karin Johnson, associate professor of neurology at UMass Chan Medical School - Baystate, thank you for being with us. And when people say goodbye to you, do they always say something like pleasant dreams?

JOHNSON: (Laughter) I don't get that one much.


THE CHORDETTES: (Singing) Mr. Sandman, bring me a dream. Bum, bum, bum, bum. Make him the cutest that I've ever seen. Bum, bum, bum, bum. Give him two lips like roses and clovers. Transcript provided by NPR, Copyright NPR.

Scott Simon is one of America's most admired writers and broadcasters. He is the host of Weekend Edition Saturday and is one of the hosts of NPR's morning news podcast Up First. He has reported from all fifty states, five continents, and ten wars, from El Salvador to Sarajevo to Afghanistan and Iraq. His books have chronicled character and characters, in war and peace, sports and art, tragedy and comedy.