My kids from time to time have gotten up in the wee hours of the morning, especially around the age of 2 1/2 to 3 years old, and I didn't know they were up. Once my son woke up and went into the office. He marked little red X's all over my X's research paper (some 25 pages). Both of us parents were sleeping, and normally our son was in bed with us. Don't know why he did that, but I had a special chain lock placed very high on the door so he couldn't get out of the house in case he did that again, but a fireman could knock it in very fast if there was a fire.
My 1st daughter usually slept later than me, so never had any major problems with her. However, my 2nd daughter got up frequently in the wee hours and
found sissors and cut her hair and my 1st daughters hair several times, even when my 1st daughter was sleeping. This was around age 3.
My kids didn't nap after age 3 1/2, so I usually would turn on PBS and let them watch for a 1/2 hour while I cat napped on the sofa next to them.
Parenting is so exhausting. You just wanna sleep, and you can't. I still crave sleep because my youngest still wakes up at 5:30 or 6:00 am every day. I try to get her to cuddle with me for a while, but it lasts no more than 1/2 an hour, then she starts wiggling.
I have started going to bed at 8 or 8:30 with the kids, so I don't feel so tired. My biggest dream is to leave the kids with my mom for 48 hours and stay in a very comfy and posh hotel, sleeping, getting room service and maybe getting up to swim at noon, only to go back to sleep for the afternoon until 8pm, then stay up until midnight and sleep again. I want to do this badly, but don't have the money to do it!
I don't think you are abusive to do this, but like other posters, I think you are taking a risk to sleep in your bed (which induces sleep so deeply for "me") and leave your kids playing without supervision.
Good luck on deciding how to handle the sitution. I think the OP who said you could always evaluate how you are handling it now, and change it, is right. Just think about it and think about the things that could go wrong in a instance. I worried about my toddlers and preschoolers climbing on furniture and getting crushed by it while I was awake. I couldn't sleep while they played unless I was very sick. I'm a single mama by the way.
Vegetarian Hindu, mother to L,P and R.