13 - wow, that's a teenager!
Sounds like he has some insecurity issues too. It also sounds like you as parents didn't make him sleep in his room from a very early age. Kinda 'lets make a deal' like you said 'you can sleep in your room for 6 days, one in ours (that's a green light for him ok?)) It's saying 'this one time' - well, this one time will be another time, and another time, and the kids know this. Think about it - what else do parents 'lets make a deal' to get them to do something, and paying them to clean their rooms or do chores? Don't even get me started there!
Adults have their rooms and kids have their rooms, period. I have never understood babies to toddlers sleeping in their parents bed. That's pure D laziness on the parents part. There is nothing wrong with the kids, the parents just don't want to get up and tend to them is all, I'm sorry.
I raised 2 girls sleeping from their crib to their 'big girls' bed'. We made a big deal about 'their own room'. This is their room just like you have your PRIVATE bedroom.
Counseling may be in order because you son is very insecure about something. Is he out for sports, play in band, etc.? That will grow him up and help him find out who he is. What does he do with his dad, go to sports outings, play ball, go riding the bike, does he hang out with friends, do you go to church and he has friends there? Young boys this age should be doing all these things.
YOU are the parent, he is controlling you my friend because he is allowed to sleep in your room as a 'treat'. STOP!
Age 13 is raging hormones getting ready to start too.
Don't you miss intimacy with your husband? What if you two were making love and when you opened your eyes saw your son laying on the floor wide awake, how would you feel then? Sex education before his eyes!
Try this - You and your husband sit down with him and tell him this has to stop once and for all - your HUSBAND needs to do the talking and you VERBALLY agree with him (your son needs to see and hear this from you)
2. If you have to wake up in the middle of the night and sees him there, your husband NOT you needs to get up and take him in his bed until he gets it! Repetition - YOU are the parents, he is the child. The reason he sleeps on your side because you are probably the one who let's him get by with things, yes?
Maybe your husband needs to step up and be a bigger part in his son's life, maybe you need to let your husband be the disciplinarian and you verbally agree with him to your son. This is your home, you son is there for a short time, then he is on his own. Off to college and out of the house to become the strong independent young man you raised.
I truly hope you aren't letting your other kids sleep in your room - if you are, you have a bigger problem and need to stop all of that right away as well. What is good for one, the others see and think it's good for them as well...STOP!
I'm anxious to hear your progressive news of healthy family living...hope I wasn't too stern, we all want healthy kids turn adults yes?