How to handle restlessness and insomnia in elderly man, 97 years old?

My dad is on Haldol and is not sleeping. We've been using Melatonin and diffusing "peace & calming" oils. He really isn't sleeping much during the day either. A few 5-10 minute catnaps is all. His sitter said he slept maybe 2 hours total from 12 midnight to 6:30 am. None before that or after.