We've let our son self-soothe himself to sleep by himself in his own bed since he was an infant (he's now 2). Lately however, after we put him in bed, his "playtime" (he talks and plays by himself) seems longer, sometimes up to an hour before he dozes off. I'm letting him go to bed a little later to see he doze off faster, but so far no success. I guess my question is. . IS it ok to leave him by himself for an hour or so before he eventually doze off, or should I be picking him up to play and get mental stimulations, tire him out and put him back in bed? Any thoughts? Thanks.