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Why Daylight Saving Time Just Isn't Healthy, According to Science

Accepted submission by Anonymous Coward at 2022-11-14 14:39:47
Science []

Daylight saving time has ended, and most Americans have turned their clocks back an hour. My sixth-grader is in heaven.

At 6:50 a.m. these days, our once testy tween zombie is now ... moderately awake and relatively lucid.

Instead of rising to gauzy predawn light, she's got glowy morning sunshine beaming around her curtains. When she sets off for school, the sun has been up nearly a full hour. Just a 60-minute change has lightened both the morning and her mood. At breakfast today, I think I even spied a smile.

On November 6, every state in the United States except Hawaii and most of Arizona switched from daylight saving time, or DST, to standard time (those two states don't observe DST). That switch shifted an hour of light from the evening to the morning. In March, we'll move in the other direction when we "spring forward," trading morning light for brighter evenings.

The United States' biannual time change has been lighting up headlines since the U.S. Senate's unanimous vote in March to make daylight saving time permanent. The Sunshine Protection Act would forgo turning clocks to and fro, repeating an unpopular experiment Congress tried in the 1970s and prioritizing evening light throughout the year. But the health case for staying on daylight saving time is pretty dim. And what such a shift could mean for adolescents is especially gloomy.

Even the name "daylight saving time" isn't quite right, says Kenneth Wright, a sleep and circadian expert at the University of Colorado Boulder. There's no change in the amount of daylight, he says. "What we're doing is changing how we live relative to the sun." When we move our clocks forward an hour, noon no longer represents when the sun is near its highest point in the sky. Suddenly, people's schedules are solarly out of sync (SN: 10/17/16).

That's a big deal biologically, Wright says. Humans evolved with a daily cycle of light and dark. That sets the rhythms of our bodies, from when we sleep and wake to when hormones are released. Morning light, in particular, is a key wake-up signal. When we tinker with time, he says, "we're essentially making the choice: Do we want to go with what we've evolved with, or do we want to alter that?"

From a health perspective, if he had to rank permanent daylight saving time, permanent standard time or our current practice of biannual clock changing, Wright says, "I think the answer is incredibly clear." Permanent standard time is healthiest for humans, he says. In his view, permanent daylight saving time ranks last.

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