HOWEVER. I still get mild pain overnight with it, rolling over in bed and wriggling around as usual. This is irrespective of the previous day's exercise and as soon as I get up in the morning it's fine. I'm not sure if it's being in one position and then suddenly moving or what that's causing it. Anyone else get this sort of thing and any idea what to do about it (apart from sleeping in a straight jacket and not listening to speedcore before bed)??
It might be the joint twisting a little and aggravating what ever it was that you had slightly damaged, or it could be the fact that part of the reason that almost anything hurts more at night is that you are concentrating on it more, as there are few other distractions compared to the daytime. It may well also be both.
I'd judge that if it isn't waking you up with a jolt of pain, then it probably isn't much to worry about and that it will get better slowly.
Alternatively, I'm sure there are a great number of special interest websites that will sell you a straight jacket to sleep in. They might throw in a complimentary set of handcuffs into the bargain.