Waking up in the middle of the night to play

Mel

My baby used to sleep from 7-8pm and wake up 7-8am (with about 2 wakeups just to feed then right back to sleep). But lately she wakes up in the middle of the night and just wants to play! She will stay up for about 1-1.5 hours just playing in her crib. Anyone else going through this? What do you do?