Child's crying during sleep

My niece smiles, cries makes different faces and seems into some situation or coversation while she is asleep. this was not very frequent untill recently. Now she cries during her sleep as if she got scared. I am curious to know the reason and that she is not facing any problem.She is only 20days old
i would also like to say thanks to the site as it has helped me before. i appriciate your great effort.

hoping to get a useful reply again