It depends, I guess. Sometimes it's really spectacular and sometimes it's the worst thing ever, so you don't want to sleep at all, and you'll do anything to stay awake. It's always strange and nonsensical, though.
[ frowning lightly at kaworu's stomach. he isn't sure if he should pity him or be envious. he reaches out to finger one of the buttons. ] Do you daydream? Have you any sort of imagination at all?