Nocturnal Walker

Z's been getting up and wandering the house at night. After she's negotiated the stairs, she'll reach the kitchen or the hallway entrance and start calling for me. Not in a distressed tone of voice, rather a "Momma, where are you? I'm looking for you (in the dark!)" kind of way. I theorize that M's restlessness/crying wakes her and then she goes looking for me to come and soothe M. The thing is, I'm already in the room, but she's bound and determined to go looking for me downstairs: go figure. We've taken to putting the upstairs gate back up.