Narcophilia
A paraphilia (fetish or kink) having to do with sleep. A narcophiliac may experience sexual arousal at the sight of their sleeping partner, at the feeling of being sleepy themselves, or may enjoy the idea of having sex with their partner while one or both of them is falling asleep. Narcophilia has nothing to do with death or dead bodies, though the word for the paraphilia known as "necrophilia" looks similar.
Joan: Were you getting it on with your girl while she was asleep? That's sick...
Tim: It's not what it looks like. She has narcophilia. She's down for it.