Lately, my son's (almost 5 mos) has been waking up crying during his night sleep every 30 min to 1 hr the first 4 hours of sleep. He doesn't seem to be crying because he's hungry or wet. The only thing I can think of is that he's been drooling a lot and chewing on things because he's starting the teething process (no teeth yet). I'm kind of bewildered by this new behavior.