Is there some sort of 15 month sleep regression that I'm unaware of? Our daughter has been sleeping through the night for at least 6 months now, and all of a sudden the last few nights she's up at 2:20, and again at 4. I'm dying over here! I'm not used to middle of the night wake ups anymore. She cries and needs to be consoled to calm down. She isn't teething, so I'm not sure what it could be!