I agree with lizzydrippin's advice, but I would take it even one step further. If your nephew can't get out of his room, I would just let him cry at the gate and ignore him. When his mom repeatedly goes and puts him back to bed, he may not be getting his way completely, but he is getting attention. This method may sound harsh, but I guarantee it will work faster. We had to use this method with our daughter when she was 3. She feeds on any attention, even if it's negative. So she could do the "get out of bed and be put back into bed" thing all night long. We finally closed the door and ignored her, and after two nights, she got the idea. She still cries a little at night just because she doesn't like to go to bed while we stay up. She does not want to miss anything. But she goes to sleep pretty quickly. Good luck!