Baby Sleep: Comforting a Fussy Baby
It is normal for babies to cry in their sleep. This is a "parasomnia" called confusional arousal that occurs in babies usually a little bit older than 3 months. Parasomnias are a spectrum of behaviors that are observed in a baby who are falling asleep.
In the past, it was widely thought that there were only three states the brain could be in: awake, asleep or dreaming. But now we know that is possible for different parts of your baby's brain to be in different states (asleep, awake or dreaming) all at the same time, which is likely the case when a baby cries in her sleep. If your baby is crying in her sleep, check on her without waking her up and then don't worry. If your child is in real pain, she will wake up.
It is also important to know that while toddlers and older humans have dreams every 60 to 90 minutes (meaning we have to sleep for about an hour or an hour and a half before having our first dream), newborns are different. Up until they are 6 months of age, newborns start their dreaming activity the moment they fall asleep. So the grimacing, fussing and occasional cries that usually occur right when they fall asleep (usually when Mom and Dad are staring at their newborn) are normal and often are from dreaming.Unfortunately, the answer to your question about your baby's sleep is not a black or white, but by and large, if your newborn seems to be asleep but struggling with something, I would just let her be.