- Darkness or some kind of nightlight?
Darkness, I find it very difficult to sleep with any kind of light.
- Noise or complete silence?
I prefer silence but I can deal with low levels of noise.
- How much clothing?
Doesn't matter, I'm comfortable so long as I'm not wearing jeans or a bra.
- Alone or with someone else?
Doesn't really matter, but other people don't sleep well when they're sharing with me because I invade their space, steal their blankets, warm my cold feet on them, and use the crook of their arm as a pillow.