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

This weekend, Chicagoans can enjoy an extra hour of sleep thanks to the end of Daylight Saving Time. But the time change can have a negative impact on health, experts say.

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

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

“Almost everyone is a little sleep-deprived, so use this weekend to catch up,” said Sabra Abbott, associate professor of neurology at Northwestern University Feinberg School of Medicine.

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

But this weekend's time change could affect circadian rhythms, the body's internal clock that controls hormones, blood pressure and alertness.

Experts say daylight saving time doesn't align with your body's natural rhythm. The change forces our bodies to adapt, said Kristen Knutson, an associate professor of neurology at Feinberg. This could lead to a transition period in which your body no longer functions as optimally.

“Your body expects you to eat something at a certain time. “You eat at a different time because the clock on the wall ticks differently than your internal clock,” Knutson said.

Doctors say the bigger problem is the time change in spring – the change from winter time to summer time. On March 9, 2025, the clocks will “spring forward” one hour, ending standard time. Then people lose a whole hour of sleep.

“In the short term, lack of sleep can be linked to car accidents or school performance, typically in the first week after the transition to daylight saving time in the spring,” Abbott said.

Mornings are darker and nights are brighter, creating a discrepancy between the body's internal clock and time. This misalignment may be linked to an increased risk of depression and even cancer, Abbott said.

Shaffer said he felt the effects of the time change in the spring.

“I'm not that alert for school, and then the whole month after that it's ruined because I can't catch up,” he said.

Medical and scientific societies such as the American Academy of Sleep Medicine advocate eliminating daylight saving time and maintaining a permanent standard time. 60 percent of countries do not observe daylight saving time, as do Hawaii and Arizona.

“People sleep more and are healthier when we have standard time than when we have daylight saving time,” said Karin Johnson, a physician and president of Save Standard Time, a coalition that advocates for permanent standard time.

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

“This weekend will be a bit of a reset for them,” she said.

Although the fall time change does not have the same impact as the spring time, doctors recommend Chicago residents to be patient with themselves, as an hour difference can throw off the schedule.

Knutson has this advice: Be careful with yourself.

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