The memory clinic here gave me a small amount of lorazepam for use in emergencies, to break a behaviour cycle. Usually that was anger related, but these days it's lack of sleep which is most likely to make think about sneaking half a tablet into a piece of fudge.
Weariness becomes a carer's constant companion at the best of times, but when it gets bad, as you're finding, it can be very bad indeed, and your ability to care... and love, suffers. So if I were you I'd be on the phone to the memory clinic seeking some fast track help. This weekend might be or problematic, but there ought to be someone manning staffing the phone who can at least note your situation and perhaps have a specialist look at your case a bit more quickly.
My experience though is that such help can be thin on the ground, especially during holidays, and it sounds like you're early in the process with them. If you're waiting for diagnosis then they will probably be very reluctant to intervene anyway, and may point you back to the GP. It'll do not harm to ask though, and don't be afraid to sound desperate. Sounds like that won't take much effort.
I'm sure someone will have other suggestions later, (possible UTI, helplines which might be open this weekend, etc) but I've had very little success with my mother when she gets into a sleepless phase. Infinite patience, and coffee, are the carer's best friends. And, of course, Talking Point.
Try cutting down fluids in the evening to limit bladder discomfort that might contribute to restlessness. Try gentle music in the background (I find The Adams Singers can help relax my Mum if she's starting to get weary under her distress). Try decaffeinated drinks during the day. Try clutching at straws!
I hope you and your mother managed took get a little sleep in the end. All dementia phases pass eventually, but sometimes our ability to cope alone runs out first. Good luck... which sounds about as helpful as a mattress made of nails! But you will get through this, eventually.