3.5 yo wants to come into our bed every night - how do I dissuade this?

Our boy has been a poor sleeper until recently when we seem to have cracked bedtime and his staying asleep for more than two hours at a time.However we are struggling to break the habit he has formed where he wakes up at random times, anywhere from 2am to 6am and comes into our room looking to share our bed. This happens maybe 6/7 nights a week.I know this is very normal, and for some it continues for years. My SO is fine with it, but I am not. She respects this but finds it difficult to action anything towards that goal. Now I am really starting to find it irritating and I want to set this boundary. I want to have my kids in bed with me by invite only, during the day (nursing and sickness aside).Does anyone have any experience in breaking this habit or ideas about how to stop it? We have already tried taking him back to his room and staying til he falls asleep - he will wake up soon after and try again; we've tried reward charts - not interested; we've tried a sleep clock - never worked on him. via /r/Parenting http://ift.tt/2bV8aZ6