The reason he keeps trying is because you eventually give in. If you didn't give in, he would give up. You need to make a decision about the "rules" of sleeping with Mom & Dad, then stick with them. The rules could include that, if he doesn't get up at night (including wandering the house)until 4am, he can come in and sleep with you. However, if he gets up before that, then he will be taken back EVERY time, including the early morning hours, regardless of whether it wakes his sister or not. The only exception would be if he was truly scared - and you would have to judge that yourself, not let him be the judge of it. If he does it the first few nights, be firm, and say, "I'm sorry you're sister woke you up (etc), and I love you very much, but you know the rule - if you get up before 4am, you canNOT sleep with us." Whatever rule you choose, do NOT give in. And, by the way, my husband is like yours - he never did want the kids to sleep with us. He considered that our private time. So, our rule was, if Dad was away for a night, one or two children (I had six) will spend the whole night with her, and the others will wait their turn. (Fighting children lost their privilege.) If Dad was home, they were taken back to their bed. If they were really scared or really sick, I would lay on their bed with them until they went to sleep. The point is consistency. If you are letting him sleep with you sometimes and not let him other times, you are sending him a mixed message. Make a rule you and your husband can both live with. Good luck!