Since she is 4 months old and previously sleeping longer, maybe she is teething. My oldest daughter started teething REALLY early, had her first tooth at 4 1/2 months! It drove me crazy, she went from colic to teething, with no break in between! (Looking back, I wish I could've just relaxed and enjoyed the stages she was going through. They REALLY DO grow up faster than you think they will---my daughters are now 23, 20 and 17, and I feel like I just blinked, and they were grown.) It's really frustrating when you're in the middle of it, though, and you are SO TIRED, all the time!! If you are a stay-at-home mom, just sleep when she sleeps, when you have to; if you work outside the home, make an agreement with your husband, like alternating nights with who gets up with her, or you get to rest whenever you want on his days off. Get creative, everyone has a different work schedule/arrangement, and YOU know what will work best for you! You HAVE TO ask, however; husbands are NOT mind readers! If you are a single mom, ask family and friends to help on their days off, so you can get some rest! I am a firm believer in bringing the baby into bed (unless one or both parents uses alcohol or drugs), as EVERYONE gets more sleep this way! I know that this is not too popular, but I did it with my three daughters, and my sister did it with her three kids. (Many cultures have "family beds" as well.) I have worked with children for 25+ years, and I'm currently in school to get my preschool teacher permit, just 5 more units! The current research on infants is to RESPOND to a crying baby, up to about 7 months old. If you don't, they WILL give up (sleep through the night) but then they have learned that their needs might not be met. I know that a lot of people will tell you to "just let them cry it out" (my mother-in-law and my aunt told me this---told me that I was spoiling them) but the truth is that you CANNOT spoil a baby under seven months old!!! Hope this helps! Just remember, this too shall pass, and you and your baby will have a stronger bond if you comfort your baby when she is upset! Please contact me if you need to talk; I care!