There is another answer... (whisper it so the experts don't hear). If he does not disturb your sleep too much, you could just let him stay and go straight back to sleep. The heavens won't fall down, he won't grow into a maladjusted delinquent- it's just about whether you and dp can get a decent night's sleep this way. Some people can (I sleep better with children in bed), other can't.
We had the same problem with DS about the same age, he was a huge lump and he did disturb our sleep. We just said if he wanted to come in he could sleep by the side of our bed. He used to bring his quilt in and do that, very little disturbance to us and he was happy. We also added a little bribary if he stayed in his bed for 2 weeks then he earn't a big Buzz Lightyear, which he did eventually.
I was going to suggest the Wake To Sleep method, but if he's waking so often, I don't know if it'd work. I can't do links, but there is a thread about it. It sorted my Dd out, but she was younger than your Ds and was down to waking just once a night(from hourly!). Hope you find a way.
DS (2.2) comes into our room, shuts the door behind him,lies downn on the little mattress we've put beside our bed, pulls the spare duvet over him and goes straight to sleep with no fuss. I only just wake up and DH usually sleeps through. far more comfortable than having a flailing child in bed with you. I assume he will grown out of it when he's ready...
Been doing this for around 2 months waking every night but coming into us with no fush for around a week. He doesnt wake 3 times a night - this is the approx time he comes to us - sometimes its 1am another time its 3am. He comes in gets in bed and goes to sleep.
I do sleep ok but Hubby gets up and goes in spare room as he's uncomfortable.
I personally think he wakes as he's cold - ie he's always kicking covers off. I pull them on at bedtime and tuck them into the side of his bed, I put him in a vest, bedsocks and warm PJ's - I even got him a full warm sleep suit but he wont wear it!
I think Im going to go with the flow and Im sure he will sort himself out. The last few months he has made changes himself so will wait for him to do this in his own time - cant last forever!!!!
PS. Although I do not encourage this, I do love the warmnest of him next to me...shsssss!!!
My daughter has done this since she was 1 (now 3 ). We have tried everything in the book and our best solution to date is having a little mattress and duvet next to our bed so she can come up and go straight back to sleep. I am not entirely happy with it but anything for an unbroken night's sleep. I think she is a light sleeper, plus she gets anxious when she wakes. I keep telling myself it won't last forever...
Had exactly the same problem at about the same age with dd. She would get in our bed and either I or more usually dh would go and get in hers! She's seven now and she doesn't do it anymore - can't remember when it stopped though it seemed to go on for ever (probably nine or ten months). To be honest, neither of us could be bothered to try and do anything about it - we took the view that she wouldn't still be doing it when she was 15 and sure enough she stopped of her own accord. I always thought the most important thing was to make sure she started off in her own bed every night - so she knew where she belonged iyswim. Enjoy it while it lasts!