The general recommendation is to change and wash bed sheets at least once a week. This frequency helps to remove accumulated dirt, sweat, dead skin cells, dust mites, bacteria, and allergens that can build up on sheets and affect health and sleep quality. Some experts say every two weeks is acceptable but weekly washing is preferred, especially for people who sweat heavily, have allergies or asthma, have pets sleeping in the bed, or have any infections or skin conditions. More frequent washing, such as twice a week, is advisable during warmer months or if the bed is shared with pets or involves night sweats. Washing sheets in the hottest water setting recommended by the care label also helps eliminate bacteria and allergens effectively. In summary:

• Weekly washing is the standard recommendation.
• Every two weeks is acceptable if the sleeper has no special sensitivities.
• More frequent washing (twice a week) if sweating, allergies, pets, or illness.
• Use the hottest water recommended for washing to kill bacteria and mites.

This advice aligns across multiple health sources and expert opinions for maintaining cleanliness and hygiene of bed sheets for better sleep and health.