Bed bugs are tiny, blood-sucking insects that infest human homes and hide in dark, secluded areas. When they feast on blood, their otherwise flat, oval-shaped bodies inflate like a balloon and transform from brown to red.
You will likely notice red stains on sheets where the bed bugs have been crushed by your body as they feed at night. Another potential sign is the dark black spots, about the same size as a pinhead, around the bed. This is bed bug excrement.