Even if you didn't travel long distances during the holiday season, you may return to work feeling as if you did.
British researchers use the term "social jet lag" to describe the mental and physical weariness people experience after days or weeks of irregular sleeping, eating and stress that experts say is similar to the travel jet lag that affects people who travel across time zones.
"Whenever we have a few days off, we have a tendency to go to sleep past our regular bed times and wake up later," said Dr. Salim Dib, assistant professor of neurology and sleep disorders at the University of Miami Miller School of Medicine. "That messes up our circadian rhythm and makes it difficult to get up at our normal time in the morning."
There are many reasons sleep experts say the holidays can wreak havoc on the body's built-in clock. In addition to getting less sleep because of social obligations, family visits or shopping, other seasonal factors play a role in disrupting sleep patterns.
"The holidays relate to doing things that are out of the ordinary, such as drinking more alcohol, eating fattier foods and more stress in general," said Dr. Nancy Collop, director of the Emory Sleep Center in Atlanta. "There may be more reflux and other things that are not good for sleep."
Fortunately, experts say, this phenomenon is temporary, but there are things people can do to facilitate a return to sleep normalcy.
"Depending on how much you delayed your sleep cycle, it may take a while to get back to regular patterns," Dib said. "It could take about a day per hour."
People suffering from social jet lag should focus on waking up at their normal time in the morning, even if it takes longer than usual to fall asleep and people get less sleep.
"Try to make morning wake-up time consistent," Collop said. "Eventually, the body will crave sleep and will get sleepier at night."
"The earlier you become active, the earlier you can be more alert and awake," Dib said.
But that's not always easy, especially in the winter months.
"It may be more difficult because it's darker in the morning," Collop said.
Experts disagree about the value of naps. Some say it can be helpful for people who haven't gotten enough sleep, but only if it's not too late in the afternoon. Others say napping can make it difficult to fall asleep at night.
Experts suggest leaving stress, whether it's holiday-related or not, out of the bedroom when it's time for sleep.
"Set aside time in the early evening to do some planning and problem solving so you can take thoughts away from the bedroom environment," Dib said. "That way, you're relaxed in bed and your brain isn't overworked."
Since stress can take a toll on sleep, sleep specialists say it's important to recognize this jet lag feeling only lasts a few days.
"Don't fret about it too much," Collop said. "It will right itself."