Dupes won't take a bed to sleep in and will rather sleep on the floor if the bed that they slept on in a rocket is access restricted.
I'm also not sure if this only applies to the ladder bed as well (as those are the only ones I use on my rockets).
Build a rocket. Have a dupe sleep in a bed (ladder?) on the rocket and then restrict access to the buildings. Notice that the dupe will sleep on the floor even if there is a spare bed open.