According to a report by the mattress selling brand, Amerisleep, an unwashed pillow could harbor 3 million bacteria after one week, which is about 17,000 times more than an average toilet seat.
The findings revealed that pillowcases and sheets contain between 3-5 million CFU (colony-forming units) of bacteria per square inch after being used for just one week.
Dr. Hadley King told Well+Good, "When you get into bed, you contaminate your bed linens with dead skin cells (about 50 million per day), sweat, makeup, lotions, hair and anything else you have picked up during the day, from pollen and pet dander to fungal mold and dirt particles to bacteria and viral particles as well.”
Therefore, experts warn washing sheets and pillow covers once a week or washing them more often if you sweat more while sleeping.
Also watch: Caution! Water bottles you use regularly might be dirtier than a toilet seat