Question for all you mommys out there. Have any of your babies gone through sleep regressions? My baby is 12 weeks now and she had been sleeping 9pm-5 or 6am for a good while and all of a sudden she's waking up at 3 or 4am again. When she wakes up I have a hard time getting her back to sleep and last night ended up having to hold her to get her to sleep the rest of the morning. I'm just at a loss because I don't know what's going on. Any advice?