<p>Ever since the time changed ( i don't really think this has anything to do with it, just that is the exact night it started) ds who is 21 mos has been waking up in the middle of the night and sometimes early a.m. just wailing! He has always been a good sleeper. He sleeps in his crib in his own room with the door shut to keep it quiet for him. We keep a music box playing at night. He is our first, so we're new to toddlerhood. Anyone know what would be causing this? </p>