Thank you, I'll try the warm milk drink and go talk to her doctor about the paracetamol / sleeping pills / mild sedatives.
I did consider that it may be a recurring body clock thing from before I moved in and changed her sleeping habits, I don't think dad bothered to wake her if she fell asleep early as I've noticed she does start snoring at around 8pm.
Anyway counting from an 8pm sleep time 3am would be a perfect 7 hours sleep, so if her body clock was a little messed up that that it would make sense. Now that I'm living with them she's not normally sleeping until 10 or 11pm (sometimes later) as I tend to wake her and she will tell me that she wasn't asleep really, she's very good at denying everything
I thought that maybe it would settle down because her body clock would change if I could keep her awake in the evenings for a month or so to tire her into sleeping through whilst finding a sleep pattern that is a little more reasonable for the rest of the family, especially me who's trying to find a job after moving here to help as her carer. It did seem to be working, we had several months of uninterrupted sleep, but unfortunately it seems to be getting worse again recently, she's back to waking up at 3am and waking us up the only difference being that she now promptly falls back asleep leaving us groggily awake and unable to settle back down properly as we have to deal with the other unpleasantness. Dad's taken to napping during the day to make up for lost sleep, and even I've found myself drifting off at times (looking after mum must be harder than I though as little to no sleep never seemed to bother me when I was living alone and working full time in England).
From both your responses though it sounds like this is a common occurrence with people who have dementia. Maybe the doctors will allow for sleeping pills to help give her a more settled night at least on a temporary basis...and thus provide the rest of the family some respite too. I can't really be drifting off once I finally find a job or I won't keep it long and that would be terrible as it's not the greatest job market out here.
I feel a little guilty because it's making me ratty which means I'm not keeping my frustrations in check as much as I would like to do and that's upsetting mum.