Sometimes after sleep, strange scratches appear on the body, as if with a blade, they go away with time as if nothing had happened. When I touch I feel pain. There is no cat. Am I asking for a scientific answer?

A scientific point of view is not needed for the damn thing, common sense is enough.

You walk and check your sofa for burst springs and bursting fittings, which you cling to with your elbows and butt, tossing and turning in your sleep.

Sometimes debris such as needles and broken glass can get under the upholstery, which are not visible from the outside, but they begin to show out under the weight of your body.