There's a Reason Why You May Need to Sleep Longer in Winter

If you're annoyed at how much sleep you seem to need in the winter, you're not alone—and scientists think they're closer to understanding why. The Guardian cites new research out of a sleep clinic in Berlin, where scientists examined nearly 190 patients who were there for help with various sleep issues. What they discovered was that people received more REM (rapid eye movement) sleep during the colder months, a find that could have implications on how people schedule how long they snooze, per research published Friday in the Frontiers in Neuroscience journal.

Researchers studied 188 of the clinic patients who slept in a special lab, where they were told to sleep as they normally do, but without an alarm clock. The length of their sleep was measured, as well as the type and quality. The scientists found that sleep time in total jumped about an hour in winter, which they say wasn't a statistically significant find on its own. What really caught their attention was the 30 minutes more of the circadian clock-driven REM sleep—the fourth sleep stage known as the "dreaming" stage—people banked in the winter months.

Which means if you're sticking to the same amount of sleep year-round, you may need to tack on some more time to compensate. The scientists note that to lend weight to their findings, they'll need to replicate the study with subjects who don't have any sleep issues, though the seasonal changes found may be turn out to be even greater in a healthy population. And experts say that these shifts in sleep habits are likely to be more pronounced in areas where there are clear seasonal shifts—at the equator, for instance, where day length hovers constantly at around 12 hours, the time people sleep should stay around the same.

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The Telegraph notes that in past eras, when food was more scarce, humans would sleep more to conserve energy in the "lean times" of winter, and that sleeping more in the colder months can also help people recover more quickly from the seasonal viruses that abound. So how to cope as researchers dive into this topic further? "In general, societies need to adjust sleep habits, including length and timing, to season, or adjust school and working schedules to seasonal sleep needs," says Dieter Kunz, a study co-author. And since we can't usually change the times we're required to show up to school and work, what that ultimately means in the winter is: Go to bed earlier. (More discoveries stories.)