Everything is just how you phrase it. For example:
-When'd you go to sleep last night?
-When'd you hop into your bed last night?
-When'd you lie down and close your eyes last night?
-When'd you take off your clothes and replace them with pyjama's for the sake of resting last night?
-When'd you get naked, put on your gown and lie down in the dark completely alone last night?
-When'd you get naked, put on your gown and lie down alone in the dark, unconcious and completely unaware of your surroundings for hours on end in a room with no lock on it?
"....Why do you ask?"
-I was just wondering.
-You seem kinda tired.
-I want to know. Tell me now.
-I want to know because I was thinking about you last night.
-I want to know because I couldn't stop thinking about you lying there still and unaware in the darkness all alone with me to watch over you.
-I already know I was watching you from the window, I just wanted to judge your answer by comparing it to when you really DID go to sleep last night so I know if you're the kind of person who lies to me.
Sure the last bit wasn't all the same response but who cares? It could be if you look it the right way.