When wearing an eye mask it's recommended to wash your eye mask at least once per week to keep it clean.
Sweat and other dirt can get onto your eye masks which can be bad for your health and prevent you from getting a good nights sleep.
Have a few eye masks available so that you can wash your eye mask often enough to keep it clean and by having more than one eye mask you can wash your eye mask and have another clean one ready so it's no hurry to wash and dry your current eye mask.
You can easily hand wash your eye mask in the sink with some soap and warm water and then ring it out by hand and rinse it.
Then just hang the eye mask up to dry either outside or inside the house.