I don’t know, maybe it will be true (let me physiologists or physiologists correct):

A cat came and sat on my stomach. Then close up. Then it completely broke down. And the more he relaxes - the more noticeably it becomes difficult! Is that how he does it?! to

My father told me as a child that it was easier to carry the living than the dead and the unconscious. And the whole thing is that the body of the most ordinary untrained living person in consciousness cannot be absolutely relaxed. Inadvertently, some muscles are strained and redistribute weight so that the carrier becomes easier. And when it is a corpse, there is no such effect, the corpse seems to be heavier. By the way, there are still trained people who in a special way know how to distribute their weight (acrobates, gymnasts, etc.).) is
Your cat on the pulse gradually falls asleep and turns off, goes into an unconscious state, so I think all the same mechanisms are working here.