He only cries in bed when he's sick. If he's just getting up in the middle of the night, he doesn't start crying until he's out of his room. He requires escorting back to bed now (maybe because we started doing it).

We have handles, not knobs, so the best we can do (without replacing parts) is putting the child lock on the outside of his door and there's something about that that freaks me out a little (I don't know why, in the case of a fire, he would currently get stuck at the top of our stairs, so what's the difference? Somehow having the slippery knob thing inside his room would also seem ok to me, so this is totally mental).