As I pointed out earlier in this very thread, the article itself mentions that there is no valid research on the long term effects of sleep training.
The only valid research says that they stop waking up their parents. This is probably due to learned helplessness, which leads us to the hypothesis in my first comment.
The only valid research says that they stop waking up their parents. This is probably due to learned helplessness, which leads us to the hypothesis in my first comment.