When does it cause concern?

DH gets up almost everynight and wakes up in the morning on the couch. He has no recollection of ever doing it. I know he has been fairly stressed lately and lacking sleep. I got very upset with him this morning because I was up half the night with LO and DH wasnt in bed. I feel like I am parenting alone. I am isually the one that gets up anyway because he has to work but its nice to have that support in bed beside me. He said he cannot help it because he doesnt know he is doing it.