I thought this as well, but you’d be surprised. Apparently it’s something that happens but I’m not sure exactly how common it is. - https://www.psychforums.com/dissociative-identity/topic90686.html- switching TAKES A WHILE. like, a WHILE. also, no, they do not switch while sleeping. if X identity falls asleep, X identity is (typically) who wakes up, not Y or Z.