Even when sheets and pillowcases look and smell fresh, they quietly accumulate sweat, natural oils, saliva, and microscopic dead skin cells every night—creating an ideal breeding ground for dust mites and triggering indoor allergies or skin irritation.
According to laundry expert Mary Marlowe Leverette, washing bedding once every seven days is essential to clear away allergen buildup before it undermines sleep quality and overall health.

Certain lifestyle factors—such as experiencing heavy night sweats, sharing your bed with pets, or recovering from an illness—require changing and laundering sheets even more frequently, ideally every few days.
To protect both your health and fabric longevity, check care labels, wash sheets separately from heavy towels using the warmest water setting permitted for the material, and ensure everything dries completely before remaking the bed.