I feel bad about it but if I was told I could still have a relationship whilst sleeping on my own, I'd definitely be pleased about that.
It always feels like a camping situation to me - a temporary must do due to circumstances rather than something I'd freely choose to do.
To me, there's almost no advantage and a lot of disadvantages - their movement waking you up, them snoring/breathing heavily, hygiene things like wind (both the other person doing it and being conscious of yours), different sleep-wake cycles, annoying cuddles, not having enough space, having to compromise on temperature, feeling uncomfortably warm having another person beside you, finding it harder to fall asleep, etc.
Definitely a part of the relationship I'd rather do without!