I remember once seeing a blind girl being interviewed on Insight, and she was saying that she has showers in the morning because they wake her up, and baths at night because they calm her down. I've been thinking about this a lot lately because I've noticed that while DD has discovered a real love for showers, they do seem to give her a lot more energy! I guess maybe it's something to do with the spray of the water everywhere or something. Could your DS be getting overstimulated, and then overtired?

Another thought I had was, could he be in pain from teething? DD has had a few nights where she's just inconsolable from what we figure is teething pain - we give her a frozen teething toy to play with. Even if it's not teething, sometimes just the suddenness of the cold in her hands seems to be enough to distract her - we've literally had her go from screaming to a curious little 'ooh!' as soon as we give it to her - and then we can work on getting her back to sleep.

Good luck, I hope you can manage to figure it out soon