need advice, brother keeps mom up all night

I need some advice from someone who's been thru this. my mother has MS and my brother is autistic, every night without acception my brother wont stay in his bed and he pulls my mother repeatedly out of bed and doesnt end up asleep until 3 or 4 or many nights at all. My mothers condition is getting worse and i think its partly due to the fact that she cant get much sleep due to the fact that my brother stays up all night and constantly bothers her. I attempt to keep him in my bed but i fall asleep and he see's his opportunity and he's gone.is there anyway to stop the madness?