This sounds so tough for your father and also for the rest of you who suffer knowing his suffering.

I would definitely consult with a neurologist. They have so many medications in their arsenal.

FYI. My husband just entered Hospice care at home. He was having a hard time sleeping because of myclonus (muscle spasms). We were prescribed Lorazepam ( low dose .5mg. if needed, just before bedtime, and can be repeated 2 more times 4 hours apart). We don't need it every night but when he is uncomfortable, it does the job. The Lorazepam is a sleep inducer, muscle relaxant, and something else I can't remember right now. I think it is usually meant for short term use. It is something that would have to be prescribed and monitored by a doctor, since it can be habit forming etc.

Good luck! I hope that you find something. As you know, the lack of sleep itself accelerates brain damage.