LO2 had been Doing progressively better the last two weeks with sleep training. Then three nights ago it all went to hell and we had no idea what was going on. Out of desperation we swaddled him at 1130 or so and voila- he slept through till morning. What the heck? He had started sleeping well without the swaddle for a week and change and now we're back to where we started? Did this happen to your LO?