Knitting Up The Ravell'd Sleeve of Care

I was asleep (har, har) when the large family dynamics topic was started this week. The topic is bedtime. This is a topic near and dear to my heart, as I would dearly love to get 12 solid hours. I'm nearly as lax in this area as organization. There are no elaborate routines. My kids have never fought me about going to bed. ( They pick much more embarrasing and socially unacceptable battles.) I say go to bed about 8pm . This is flexible depending on when we get home. I help 2yo get in her jammies, and 2yo and 4yo to brush their teeth rather than chug the toothpaste. I take 7,4 and 2yo upstairs and they fall asleep. Sometime about 9pm the 10 and 12 yo get sent upstairs. They are far beyond jammies and can do their own teeth! 13yo gets encouraged to call it a night at 10pm.
To start with all my babies have slept with us until they moved themselves out. This happened relatively early with all of them so it hasn't been an issue. If they wander in sometime at night they crawl in bed with us. The 4 and 2 yo are the only ones who do this. I'm convinced that is because they co-sleep together. Sort of like a litter of puppies, cuddled up on somebody's floor upstairs. They all do have beds, but they prefer to huddle together. Maybe we should heat their rooms? JK.
Now getting them to sleep past 5am. That is the problem I need to solve!