For most people, the missing hour Sunday means a sleepy Monday. But for some -- particularly those who aren't big on mornings to begin with -- it takes a heavy toll on mood and productivity, earning blame for car accidents, workplace injuries and stock market dips.
"It's an interesting paradox, because traveling one time zone east or west is very easy for anyone to adapt to," said Dr. Alfred Lewy, director of Oregon Health and Science University's Sleep and Mood Disorders Laboratory in Portland. "But in daylight saving time, the new light-dark cycle is perversely working against the body clock. We're getting less sunlight in morning and more in the evening."
The body clock is a cluster of neurons deep inside the brain that generates the circadian rhythm, also known as the sleep-wake cycle. The cycle spans roughly 24 hours, but it's not precise.
"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 grumpy.
With time, the body clock adjusts on its own. Here are a few ways to help it along.
Soak Up the Morning Light
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 at dawn. Sleeping by a window won't cut it, Lewy said. The sunlight needs to be direct.
Avoid Evening Light
Resisting the urge to linger in the late sunlight Sunday and Monday also can help the body clock adjust, Lewy said.
Try a Lose Dose of Melatonin
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.
Taking a low-dose (less than 0.3 mg) of melatonin late in the afternoon Friday through Monday can help sync the sleep-wake and light-dark cycles. But be careful: Although melatonin is sold as a dietary supplement, it can cause drowsiness and interfere with other drugs.