As you might guess, the main and most common cause is still sweating. And for good reason: your pillow will gradually and irreversibly turn yellow every night because of it. Sweat from your body is absorbed into the fibers of the pillow before it reaches the surface. But while sweat is still the most common cause, other factors, such as saliva, also play a role.
The leaked fluids contribute to the yellowing of the pillow, which absorbs them. Moreover, this discoloration is not just an aesthetic problem; it is evidence that bacteria and dust mites have settled deep between the fibers. This is natural, as these creatures live in humid environments, which can cause conditions such as asthma, allergies or rhinitis.
