If you need to sleep on a mattress that has a damp spot from pee, you can take steps to protect yourself and sleep comfortably. Start by blotting up moisture then cover the damp spot with a fresh, dry towel. Next, place a plastic trash bag over the towels to create a barrier between the wet area and your bedding. Finally, add your bedding on top of the plastic bag. This layering technique can help prevent the moisture from seeping through to your bedding and make your sleep more comfortable. But, it's important to clean the mattress as soon as possible to prevent permanent stains and lingering odors.