Does she have a bedtime routine? At 4 months she should know the difference between night and day thus should sleep through all night waking only for feeds. I use the glow baby app to record my baby's feeds and sleeps etc. From that I realised my LO can only go 1hour to 1 1/2 hours before he's very fussy for another nap. So before bedtime after his last nap at 7/8ish I'll let him play for half an hour then start winding him down, baby massage with oil, bath time, then read a story, turn all the lights off apart from a night light and feed bottle and put to bed. From then on everything you do until morning should be in nighttime mode. Any feedings should be with dim lights, no talking to her at all. If at 4am she wakes and wants to play, you still keep in night mode. Let her play in her crib until she frustrates herself and realises it's night and she's not going to get attention or lights and then maybe rock her (still no talking to her) and feed her and put her back down. It may be a few nights you have to do this but it should work hopefully! My LO sleeps from 9pm to 8am ish. He's not any schedule simply a pattern. His day time naps range from 15 mins to an hour or so. He's nearly 3 months. x

i came across an article the other week to give your baby a bottle before she goes to sleep and then give her a dream feed before you go to bed they sed it makes them sleep longer because they wont be hungry.. i dont know if it works or not but worth a try :) x