If you struggle with the switch to daylight saving time, you might feel enlightened to learn it's not just in your head. It involves an interplay between the clock, sunshine and your body at a cellular level.
Planning ahead to shift clocks forward one hour, which happens this year on March 13, could ease the transition, say sleep experts, who see the time change as a serious health threat.
"We all lose an hour of sleep from time to time," said Dr. Beth Malow, director of the sleep division at Vanderbilt University Medical Center in Nashville, Tennessee. But daylight saving time is more than that.
For starters, "it's not just that one hour," Malow said. It can lead to more.
High school students, for example, lost an average of 32 minutes of sleep on weeknights following the shift, for a net loss of 2 hours, 42 minutes that week, according to a small 2015 study in the Journal of Clinical Sleep Medicine.
According to the American Academy of Sleep Medicine, effects of the time change might last for months. Some of those effects appear serious.
"People are more prone to having some types of cardiovascular events because of the change in time," said Girardin Jean-Louis, director of the Center on Translational Sleep and Circadian Sciences at the University of Miami Miller School of Medicine in Florida. Research shows the risks of having a heart attack, stroke and episodes of an irregular heartbeat called atrial fibrillation can increase after the time change.
The shift to daylight saving time differs from the jet lag that accompanies travel because of our biology, Malow said.
Many of our organs have internal clocks, she said. A key signal for those body clocks, or circadian rhythms, is light. If you travel from Chicago to New York, you lose an hour, but a shift in the light cycle accompanies the change. When it's time to spring forward, you don't get that cue.
Younger, healthier people may adjust more quickly, Jean-Louis said. But for older people, or those with medical conditions that affect their sleep, "it's a much, much harder task to try to get back to schedule."
Although some defend daylight saving time for economic and other reasons, Jean-Louis and Malow, like the American Academy of Sleep Medicine, said a fixed year-round time would be the healthiest approach. But, as Jean-Louis said, "that's not going to happen anytime soon."
So, they offered this advice:
– Take sleep seriously. Most adults need at least seven hours a night, the Centers for Disease Control and Prevention says. Older and younger people may need more. Yet a third of U.S. adults are sleep-deprived, CDC data show. The shift to daylight saving time can exacerbate that, Malow said.
– Make a gradual shift. Most people don't adjust until the day of the change, Jean-Louis said. But if you start a few days ahead, shifting bedtime by 20 minutes a day, "it's easier for you to get accustomed to the new clock."
– Don't sleep in on Sunday. It's tempting, Malow acknowledged. "But really try to get up at your usual time and get exposed to light, because that bright light in the morning will help you wake up, and it will also help you fall asleep easier at night."
– See the light. Jean-Louis also emphasizes light exposure in the morning. "You could wake up one hour early and take a walk facing east so that you have exposure to the sun as it rises." Again, starting a few days ahead of time is important, he said.
– Coffee? OK, but be careful. Malow and Jean-Louis are coffee drinkers. And both say it's great for keeping you alert in the morning. But only drink it early in the day. "If you're having coffee at about 3, 4 or 5 p.m., that's just not good," Jean-Louis said, "because it can trigger a cascade of dysregulated sleep cycles, which influence your ability to get a good night's sleep."
– Don't use alcohol to help you fall asleep earlier. "That can actually interrupt your sleep in the middle of the night," Malow said.
– Limit screens. The blue light from screens is "kind of like being exposed to sunlight late at night," Malow said. So limit time looking at them, especially at bedtime. "Try reading a book or do something that doesn't involve that light. If you absolutely have to be on your computer or phone, use settings that help cut down on the light."
– Help the kids. Parents of small children know that time changes can be rough. But most of the advice for adults also works for kids, Malow said. "Try to get them to bed a little earlier the few days leading up to it," she said. And "pay attention to getting them out in the bright light as much as you can once we make the change so they can acclimate."
– Address persistent problems. If someone has a regular problem falling or staying asleep, or if they have signs of sleep apnea such as snoring or excessive sleepiness, "they really should get it checked out" by a doctor, Malow said. Sleep is important not only for feeling good, "but it can make a tremendous difference on our health, including our heart health."
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