Sleep Problems 3 year old

My 3 year old daughter (turnig 4 in September) has a problem with sleeping. She goes to bed fine. But since she has been littel she wakes herself up anytime from 03:00 am, by first talking in her sleep and the sobbing like someone died. And this is a nightly thing.

We have had a good routine since she was a baby. This started when she was about 1.

Any suggestions? Will a sleepsack/weighted blanket help?