As Americans prepare to spring forward on Sunday, some might dread the looming loss of an hour of sleep. In fact, over half of U.S. adults now oppose daylight saving time, according to a recent Gallup poll—and the reason might be backed by science. Experts say the time change does more than just make the mornings a little tougher, it impacts our health.

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“The spring time change leads to society-wide sleep deprivation,” says Jennifer Martin, former president of the American Academy of Sleep Medicine and professor of medicine at the David Geffen School of Medicine at UCLA.

A big impact
While losing an hour of sleep might not sound like a major change, Martin says it has a big impact on our health—in large part because most Americans are already not getting enough sleep. “Many Americans are already chronically sleep deprived or suffering from sleep disorders,” she says. “This extra disruption amplifies any of the symptoms that they're already having.”

The time change also brings with it other adverse health impacts due to changes in our circadian rhythm. “Our circadian rhythm is our internal clock, and it is very tightly linked to the 24 hour day,” Martin says. “[Daylight saving] actually alters the relationship between our internal clock and the external environment.”

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Moving to daylight saving time means that our circadian rhythms are no longer aligned with rising and setting of the sun—and that impacts our health. “When we're on Standard Time, the daylight hours are more closely aligned with our circadian rhythms,” says Martin. That changes when the clocks spring forward: “When we shift to daylight saving time, it's dark later in the morning, and that is not good for our overall health and well being.”