This Disturbing Study Will Make You Want to Wash Your Sheets More in the Summer

It’s hard to beat the feeling of settling into a pair of crisp, freshly laundered sheets at the end of the day. But in reality, data shows that people tend to wash their sheets a lot less than they should. And funky-smelling bed linens hide a much bigger problem: A bed teeming with dust mites, bacteria, and mold. This visual might be enough to get you to make laundry a weekly priority, but a new report reveals that this skin-crawling situation is even more nefarious during hot summer nights.

The process of getting freshly laundered sheets on my bed (and over my duvet) tops the list of my least favorite chores. However, spending more than a week snoozing in the same sheets can lead to your bed becoming a hotbed of germs, according to experts — and a new report from mattress company Amerisleep argues that you should be washing your sheets even more frequently during the warmer months.

Certified Sleep Science Coach McKenzie Hyde revealed that higher temperatures as well as higher humidity during the summer can exacerbate issues that turn your freshly laundered sheets into less-than-sweet-smelling linens in a recent study.

Dr. Nilong Viyas, MD, MPH, a board-certified pediatrician and the company’s sleep consultant, says that this reality means you might want to consider washing your sheets more frequently.

“I tell families to think of their bedding the same way they do their clothing: sheets and pillowcases collect sweat, skin cells, and bacteria quickly. Our testing showed that after just one week, pillowcases and sheets harbor millions of bacteria. Washing once a week is the minimum to keep those levels in check, and in hot weather or for people with allergies or sensitive skin, washing more often helps maintain a clean, healthy sleep environment,” she says.

While you sleep, any impurities on your skin as well as sweat, sebum, skin cells, and oil soak into your sheets, mattresses, and pillows, creating a breeding ground that’s ripe for bacteria growth. Extra sweat, as well as a warm, moist environment, can cause this type of bacteria to increase over time, according to the Amerisleep report.

Hyde called heat and moisture “bacteria’s best friends,” explaining that “when we sweat more in summer and don’t increase how often we wash or air out our beds, the result is a perfect breeding ground for bacteria and allergens.”

This finding is particularly noteworthy, as a February 2024 report found that Americans reportedly wait 24 days on average before swapping out their dirty linens. But Hyde recommends increasing the frequency of how often you wash your sheets during the summer from once a week to twice a week. This is especially important if you sweat at night or you’re sleeping with pets, who can add pet dander into the mix.

The tedious, hours-long process of swapping out your bed linens can seem like another chore that you don’t want to add to your plate, but the study also found that a 7-year-old mattress may have a colony of over 16 million bacteria units, while pillowcases and sheets can house up to 12 million of these units after just four weeks. The longer these germs are allowed to breed, the more likely they are to cause skin irritation, infections, as well as other health issues.

In addition to washing your sheets twice a week during the summer, Hyde also recommends using moisture-wicking sheets made out of natural fibers, using a dehumidifier in your room if needed, and taking a shower before bed. In addition, you might want to consider using a UV light or exposing your mattress to natural light every now and then to kill bacteria on its surface.