Okay, maybe not, but I can’t think of any good explanations.
My sister is severly autistic, and so she has full-time caretakers living in the house- one for weekends, and one for weekdays. Her bedroom is actually divided into her own bedroom, her bathroom, and her caretakers’ bedroom. Let me give you a very bad visual:
I knpw that’s as clear as mud, but the evil coding won’t let me leave any spaces. So Sis’s bed and the babysitter’s bed are in seperate rooms connected by a wooden hallway.
This morning, Weekend Sitter was talking about a scare she had when we were away. She heard footsteps in the hallway, and thought it was some intruder bothering sis. She told herself she was being silly and got up. Sis was fast asleep in her bed.
This was when my parents mentioned that they’d ocasionally heard the footsteps, too. They’d assumed it was Sis or Sitter pacing.
It turned out that Weekday Sitter had heard the footsteps as well.
We can’t figure out who or what has been walking around in the night. The only people in the suite are Sis and her helpers. Even the cats don’t go in there at night.
Could be the boards “settling” as the temperature changes during the night. You could try leaving the windows open on a warmish day, then closing them and turning on the AC. Does the sound occur then?
They did in my house, if someone went to the bathroom at night (just for instance) a little bit later they would pop in a rhythm similar to someone walking. It sounded remarkably like someone walking heavily on a hardwood floor.
I wonder if your sister might have some spasms or figity movements that vibrate through the bed, then the floor, and through the house and seem to sound like footsteps.
“Silent nights” are never really silent and the ambient noise can take some weird formations, including what one would swear are voices.
Either that or your sister’s condition may be sparking a mild poltergeist effect in the ether.