tarotgal

It would probably be more accurate to say that when he was actually up killing or doing whatever he did, he thought he was sleeping. Rather than saying the reverse.
Because of course there had to have been some time when he actually did physically sleep (because we saw him dream at least once). So while sleeping was a necessary condition for him to be up and killing, etc., every time he went to sleep it doesn't mean he was up and doing things.
In other words, don't worry in fics about putting him to sleep. It doesn't mean he'll necessarily slip into another personality at that point.

Glad the HP reference helped. There's a dozen other movies I can mention that illustrate the same thing but I knew you were familiar with that one. I love in HP5 when Ginny angry at Harry because he's so angsty and doesn't go to her about his Voldy-controlling-him suspicions. And she's all "Did you have long blackouts where you'd wake up after a long time and not remember what you'd been doing or what happened? No? Then he's not controlling you!" LOL She's such a rational, feisty chica. Love her :-)