intelligence is famously hard to define but I think a big chunk of it is associating ideas. most people have set pathways, x associates with y and so on. the

intelligence is famously hard to define but I think a big chunk of it is associating ideas. most people have set pathways, x associates with y and so on. the more intelligent cross-reference more things. while you are asleep your brain plays with associations. I would bet that someone who didn't dream would do substantially worse on cognitive tests of all sorts.