-- intro: Daylight saving time 2015 will begin on Sunday, March 8 at 2:00 a.m. That means it's time to spring forward, but the sweet act of moving the clocks an hour ahead can deliver a blow to your sleeping schedule
That's because people are experiencing more than just jet lag this time of year. They're dealing with a new light-dark cycle.
"It needs a signal every day to reset it," said Lewy.
The signal is sunlight, which shines in through the eyes and "corrects the cycle from approximately 24 hours to precisely 24 hours," said Lewy. But when the sleep-wake and light-dark cycles don't line up, people can feel out-of-sync, tired and downright grumpy.
With time, the body clock adjusts on its own. But here are a few ways to help it along.
quicklist: 1 category: How to Spring Forward title: Soak Up the Morning Light url: text: Getting some early morning sun Saturday and Sunday can help the brain's sleep-wake cycle line up with the new light-dark cycle. But it means getting up and outside at dawn. Sleeping by a window won't cut it, Lewy said. The sunlight needs to be direct because glass filters out much of the frequencies involved in re-setting the sleep-wake cycle.
quicklist: 2 category: How to Spring Forward title: Avoid Evening Light url: text: Resisting the urge to linger in the late sunlight Sunday and Monday also can help the body clock adjust, Lewy said.
quicklist: 3 category: How to Spring Forward title: Try a Low Dose of Melatonin url: text: While light synchronizes the body clock in the morning, the hormone melatonin updates it at night.
The exact function of the hormone, produced by the pea-size pineal gland in the middle of the brain, is unclear. But it can activate melatonin receptors on the neurons of the body clock, acting as a "chemical signal for darkness," Lewy said.
A version of this story previously ran on ABCNews.com.