Daylight saving time ends on Sunday — and comes with a health warning

This weekend, Chicagoans will savor an extra hour of sleep thanks to daylight saving time ending. But the clock change can affect your health, experts say.

Daylight saving time, which runs from March to November, ends at 2 a.m. CST on Sunday. Clocks will “fall back” an hour to put Chicago into standard time. After this weekend, the sun will set an hour earlier and rise an hour earlier.

On one hand, it's a chance to make up for lost sleep.

“Almost everybody is a little bit sleep deprived, so take advantage of this weekend to catch up,” said Sabra Abbott, an associate professor of neurology at Northwestern University Feinberg School of Medicine.

Tzvi Shaffer, an 18-year-old from Rogers Park, said he appreciates the extra hour to snooze, which will help him recover and focus on academics.

But this weekend’s time change could affect the circadian rhythm, the body’s internal clock that controls hormone, blood pressure and attention levels.

Experts say daylight saving time doesn’t align with your body’s natural rhythms. The switch forces our bodies to adjust, said Kristen Knutson, an associate professor of neurology at Feinberg. That could lead to a transition period when your body is not working as optimally.

“Your body's expecting you to eat at a certain time. You eat at a different time, because the clock on the wall is different from what your internal clock thinks,” Knutson said.

Mornings are brighter and nights are darker, causing a mismatch between the body's internal clock and the time. That misalignment can be associated with an increased risk for depression and even cancer, Abbott said.

Doctors say the bigger problem is the clock change in the spring — going from standard time to daylight saving time. On March 9, 2025, clocks will "spring forward" an hour, ending the standard time. That’s when people lose a full hour of sleep.

“In the short term, sleep deprivation can be associated with car crashes or school performance, typically in that first week after the spring switch to daylight saving time,” Abbott said.

Shaffer said he feels the effects of the spring time change.

“I’m not as awake for school, and it wrecks the whole month afterwards because I can’t catch up,” he said.

Medical and scientific societies, like the American Academy of Sleep Medicine, support getting rid of daylight saving time — keeping a permanent standard time. Sixty percent of countries don’t observe daylight saving time, nor do Hawaii and Arizona.

“People get more sleep and are healthier when we are on standard time, than when we are in daylight saving time,” said Karin Johnson, a doctor and president of Save Standard Time, a coalition advocating for a permanent standard time.

Most people never fully adapt to the daylight saving time, so their bodies are always a bit out of alignment, Abbott said.

“This weekend is going to be kind of a reset for them,” she said.

Though the fall time change doesn't have the same effect as the spring one, doctors recommend Chicago residents be patient with themselves, given that an hour difference can throw off schedules.

Knutson has this advice: Go easy on yourself.

“Don't drive if you're too tired. Don't try to schedule really important meetings first thing on Monday morning,” Knutson said.