While there is no rule of thumb of when to wash your bedding materials, it all depends on how you use and the amount of usage there is.
Sheets and Pillowcases
While we are comfortable in bed, from sleeping to just relaxing after a tiring day at work, it is important to realize that you are not alone. From dust particles to microscopic dust mites settle in while you enjoy your bed to the fullest.
It is recommended to wash your sheets regularly to reduce the chances of the bacterial organisms which is unpleasant for humans. Washing your sheets once a week is a norm, but, in cases if you or any member of your family is not feeling well, washing your sheets more often is highly recommended.
While using a pillow protector under your pillowcases is highly important, if you don’t use one, then wash your pillows each consecutive month.And, If you make use of pillow protectors and under your pillowcases, just wash your pillows three times a year.
It is recommended to wash Pillow protectors, once a month.