If you shower before bed, you’ve probably wondered whether sleeping with damp hair is a problem. Maybe you’ve heard it could make you sick, or that it can damage your hair or skin. What’s the truth?
Let’s address the “it can make you sick” myth first.
“This idea seems to fit into the old bit of folklore that getting yourself chilled and wet will cause you to come down with a cold,” says Dr. William Schaffner, a professor of medicine in the Division of Infectious Diseases at Vanderbilt University Medical Center.
While this idea persists, Schaffner says it was long ago disproved. It’s true that you’re much more likely to catch a common cold during the winter months. But this has to do with the ways respiratory viruses proliferate and spread, he says. “You cannot catch a cold from being cold,” he adds.
Another wet-hair rumor is the idea that harmful bacteria will colonize your pillow. Illness-causing bacteria and viruses don’t appear spontaneously, and so you’re not going to make yourself ill by getting your pillow a little damp at night, Schaffner says.
But there is a possible exception. Some research has shown that pillows—especially those made with synthetic materials—can harbor asthma- or allergy-triggering molds and fungus. These microorganisms tend to do well in damp environments, and so do dust mites, says Dr. Payel Gupta, a board-certified allergist and spokesperson for the American Lung Association.
Gupta says there’s no evidence that people who sleep with wet hair experience more allergy or asthma symptoms, so any concerns about wet hair are theoretical. But if you wake up with a stuffy nose, itchy or watery eyes, breathing problems or other allergy or asthma symptoms—or even if you don’t—you should wash your pillow cases and sheets in hot water at least once a week to reduce your exposure to any potential irritants.
When it comes to the health of your hair and skin, there may be a few other legitimate reasons to worry about water-logged locks.
“Generally, it’s thought not to be good for hair to sleep with it wet,” says Dr. George Cotsarelis, a professor of dermatology at the University of Pennsylvania’s Perelman School of Medicine. Over time—anywhere from a few days to weeks or months—water can degrade a hair follicle’s protective outer layer, which is called the cuticle, he explains. Once that cuticle breaks down, water can penetrate it and rupture the follicle’s inner cortex. The resulting damage can lead to breakages, he says, as well as a loss of shine and elasticity.
But it’s worth noting that almost anything you do to your hair—from brushing and blow-drying it to coloring it or exposing it to the sun—can damage it. While sleeping with wet hair may not be optimal, using conditioner can help restore and repair it, says Dr. Adam Friedman, professor and interim chair of dermatology at the George Washington University School of Medicine and Health Sciences.
Friedman says the same is true of any potential skin issues that could arise from sleeping with wet hair. If you’re a side or stomach sleeper, pinning wet hair between your pillow and the skin of your face could cause some irritation, he says. Also, as the water in your hair evaporates, this could promote dryness on your face or scalp, he adds.
But a lot of people sleep with wet hair and don’t seem to have any problems, he says. And in some cases, wet hair may actually be a helpful sleep aid. Research has shown that cooling your head at night helps calm the brain’s metabolic activity in ways that promote sleep onset and restorative ZZZs.
There may be some mild risks associated with going to bed with wet hair. But of all the health concerns you could worry about, this one shouldn’t keep you up at night.