Daylight Saving Is a Trap

When people say they like the time change, what they really mean is that they like summer.

GIF of two eyes with clocks as the eyeballs
Adam Maida / The Atlantic

This week, the “Sunshine Protection Act” passed the Senate. The bill, which would make daylight saving time permanent, is popular with the public; people hate switching their clocks back and forth. And who doesn’t like sunlight?

But daylight saving time isn’t good for us. It’s an artificial jump forward from standard time, which is more aligned with the path of the sun. (At noon during standard time, the sun is actually at its highest point in the sky.) Our bodies evolved, over millions of years, to be exquisitely attuned to the sun’s rhythm. When we wake and see sunlight in the morning, it trips off a cascade of chemicals in our brains that coordinate mental and physical health. Morning sunlight (even through the clouds on a winter day) is vital.

Book cover of Generation Sleepless
This post is adapted from the authors’ forthcoming book.

Shifting our clocks every March so that many of us have to wake up before sunrise takes a toll. We can move the hands on a clock, but we can’t fool the body. The shift raises stress levels and inflammation, shortens our sleep, and increases depression. In the week after daylight saving time begins, the incidence of heart attacks and strokes goes up significantly. A recent study found a 6 percent rise in fatal car crashes in that same period.

Daylight saving time is particularly dangerous for teenagers, who are already struggling to stay in sync with the sun. Teens have a natural delay in their biological clock. This phenomenon is seen across cultures—and even across species—and may be evolution’s way of giving teenagers more independence. Their melatonin—the drowsiness hormone—rises later in the evening, prompting them to go to sleep later and wake up later than the rest of us. Too-early high-school start times already make healthy sleep difficult for teens, given this natural delay. The darker it is in the morning and the sunnier it is later in the day, the harder it is for them to get to bed on time. The result is shortened sleep, an increase in accidents, and a higher risk of depression.

Modern-day adolescents are already the most sleep-deprived population in human history. By their senior year, high-school kids on average are getting six and a half hours a night, when they should be getting eight to 10. Teen sleep has been on the decline for decades, and now, one in five teens sleeps five or fewer hours a night. There is a notion that teenagers can get by skimping on sleep, but it turns out the opposite is true: Sleep becomes more vital in the teen years as kids go through drastic developmental changes in the brain and body.

A sleep-deprived brain is slower to react and makes more mistakes. It also skews toward sadness and anger. Recently, the surgeon general outlined his concerns over a growing mental-health crisis, citing higher levels of depression and anxiety among young people: “In 2019, one in three high school students and half of female students reported persistent feelings of sadness or hopelessness”—an increase of 40 percent from 2009. The reasons for deteriorating mental health are complex, but sleep loss and a chronic struggle to stay in sync with daytime schedules are big factors. One study found that kids who were sleep-deprived were three times as likely to have symptoms of depression. A new study in the Journal of Adolescent Health finds that for kids ages 11 to 14, sleep was one of the top predictors of positive mood and protectors against anxiety and depression during the pandemic.

Daylight saving time is already unhealthy. You might have the sense that just adapting to it permanently would be better, because we would soon get over that immediate sense of jet lag, but that’s not the case. We’re unaligned with the sun all season long, even if most of us aren’t consciously bothered by it. The big reason daylight saving time never seems so bad is that the shift happens when the days are getting longer. When people say they like it, what they really mean is that they like summer.

But daylight saving does not actually add sunlight to the equation (despite what politicians are saying). If the House passes this bill and it becomes law, we’ll face very long, very dark mornings every winter. In some areas of the country—especially those in the westernmost part of each time zone—the sun won’t rise until 9. Teenagers will feel like they’re waking up for school in the middle of the night and will take calculus exams under fluorescent lights without ever seeing morning sun. They’ll miss most of their REM sleep, or dream sleep, which happens in the early-morning hours and is essential to mental health.

This is clearly a bad idea. So why is it happening, besides the appeal of the bill’s sunny name? Maybe influential business groups like the idea that, with an extra hour of evening sunlight, people will drive more and spend more. But what we actually need to do is sleep more.

If the bill does pass, we’ll need to protect teenagers. We could, for instance, move school-start times to 10—but just try bringing that up at your next school-board meeting. Fortunately, a much better solution exists, one that preserves morning sunlight in the winter without forcing us all to fiddle with our clocks twice a year. We could just do that once more this November, and then stick with standard time.

Standard time is nothing fancy; it’s just the natural way. Why not make it permanent instead? Our bodies already want to follow the sun. Our clocks should do the same.

This post is adapted from Turgeon and Wright’s forthcoming book, Generation Sleepless: Why Tweens and Teens Aren’t Sleeping Enough and How We Can Help Them.

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