To be influenced by s.t. so that one talks about it/them in one's sleep or does the actions of whatever one is being influenced by in his sleep. [This always has the prefix ni-/l-/n- and always focuses on the one doing s.t. in his sleep].
Look at that guy, he's acting like he's playing basketball in his sleep (lit. he's being influenced by basketball in his sleep).
He talking about his girlfriend in his sleep (lit. he's being influenced by his girlfriend in his sleep).