There's been thousands of threads on this subject - the advanced search function is very useful.
The doctor/GP or whatever should point you at the Community Mental Health Team and in a lot of areas you don't need a referal and can just call them yourselves. Google is your friend. They are the people to deal with these kinds of problems.
BUT these issues are NOT 'sleep problems' they are agitation problems and are very common problems for people with dementia. Trying to treat them as sleep problems will not solve anything.
It may take a few appointments and you do have to take a trial and error route but the CMHT in your area should help. They are the experts. And they range from registered nurse to consultant levels so can escalate if necessary.
Our community mental health team is within the same department and building as the Memory Team and GP referred dad to them on 10th May this year. The memory team replied back to GP by letter and myself via phone call that they do not do anymore once they diagnose patients with Dementia. They advised GP needs to refer to a medical specialist for anything patient requires. I have been around the houses with this but postcode lottery is real and the reality is that our local CMHT/Memory Team DO NOT do follow up appointments or see patients again once they diagnose, everything is passed back to GP to refer to relevant specialist as and when issues arise. Since dads diagnosis in 2016 dad has not had a meds review nor had a review about his Alzheimer's, no one is interested.
I have had a breakdown many years ago and had the input of the CMHT which were fab for me, they had so much help for me and I couldn't knock them. To be in this situation now and not be getting help for my dad and it being left in the hands of our GP whom has no insight into Alzheimers and refuses to refer to relevant specialist is truly heartbreaking.
To know I'm not the only carer in the UK to experience this is shocking, I was speaking with another carer yesterday and the memory team have not had anything to do with her mum for 8 years...discharged immediately on day of diagnosis, at least we got approx 2 months from them until dads meds were deemed fine and that was it, back in GPs care.
I also spoke with another carer whom has nothing but praise for their local memory team, GP can refer to them and they get the care they need.
If we all had the same level of care in every local authority it would be a wonderful thing but the reality is that we do not. It was the same thing when I was trying to get help for my youngest son 17 years ago who is on the autistic spectrum. Some local authorities are fantastic and some are not, that's the reality of the country we live in.
I am doing all I can and I will not stop because if I don't fight for my daddy no one else will! Yes Google is fab it's just my local authority that is not, I can't control the level of care our authority has to offer. Our Age UK is poor too and they offer nothing but to help fill in disability forms and benefit forms, they don't even help with filling in POA forms as I contacted them for assistance with our POA form...I was in shock when they told me their particular office does not do anything more than help with filling in them specific forms. I said how Age UK does XYZ and I have heard this from speaking with other carers, nope not our Age UK! It really is a sad state of affairs and in the meantime our elderly and disabled are left to rot