How to deal with sundowner's behavior with my husband diagnosed with Alzheimer's?

A friend of mine had good luck with keeping the interior house lights UP until bedtime. Grandpa would relax if the rooms seemed to have daylight. Then she would turn them down at 10 PM and he would go to bed.
For my MIL, a small glass (3oz) of red wine would mellow her out.
Try some hot cocoa if he likes that.