I think I agree with Alison. Weirdly, both of my children are dry at night, and have been since before they were one year old. Of course, dd isn't potty-trained yet, but she doesn't pee on average until a good 20 minutes after she's awakened most days. DS was dry at night too on his own. In contrast, my niece, who is 5 and just started kindergarten, still wears pull-ups to bed and obviously is not physically ready to be dry at night. You'd think it'd be the opposite with my kids vs. my sister's kids, because it seems like I'm up peeing once or twice every night! lol I really think it's a physical readiness that can be trained, but perhaps with great frustration for everyone? Just my two cents. We'll see how I feel when dd is being "trained". Good luck with your decision.