When you walk the Camino de Santiago you will stay at a lot of albergues and hostals. These places all provide a thin sheet for the pillow and bed. The only problem is that the quality of this thin sheet is not very good. You can still get bed bug bites and be exposed to other bacteria on the bed. The best defense against this is to use a sleeping bag liner, not a sleeping bag. A regular sleeping bag is too bulky and is used to sleep in the outdoors. All you really need is the cotton casing to sleep in.