IDK who you wanted this for, so I’m going to answer them for Brook
∞ = What does the character usually wear to bed?
Brook is a traveller and a mercenary - she's on the road a lot. Before that, she was in a dorm with dozens of apprentices. As such she's accustomed to sleeping in clothes and sometimes armour. The idea of sleeping naked or in her smallclothes is a very alien one and even if she's had sex with someone, she won't fall straight asleep like that. She'll put something on, a shirt and trousers or something. Not doing so leaves her feeling very vulnerable.
♥ = Do they prefer to sleep alone? With a partner/stuffed companion?
She's more used to sleeping alone of course, but she can be extremely cuddly when sleeping alongside someone else, even platonically. She's a woman who likes touch who doesn't get much [in non-ships], so curling up with a partner is a lovely experience for her. Doubly so that she feels a little more protected, so she's more likely to fall into a deeper asleep and stay that way.
☯ = Any odd sleeping habits?
She makes 0 sounds when asleep, and unless she feels safe, she won’t move either. Not snoring, not even heavily breathing, even her nightmares are silent and still. Naturally this can be super disconcerting for anyone to stumble upon, and she’s been woken by people thinking they’ve found a corpse before. It's a protective measure though - sleeping out in the wilds alone, it's an advantage to stay small and quiet.
She can also, on the topic of sleeping in the wilds, fall asleep anywhere - but never deeply, and she can and will launch at you with a knife if you disturb her and she perceives you as a threat.
☁ = How often does the character dream?
Nightly, mostly nightmares. Her 'true' nightmares range in topic from Kinloch and Uldred to the Archdemon, to the Broodmother and the Werewolves. These are rarer than her Blight Nightmares, of which she can have two of three a night, due to being sensitive to the Taint. She also rarely wakes up due to these nightmares - she’ll sleep as they fade into one another.