18 months waking up screaming

Ka

My DD use to wake up happy in the mornings as long as we let her wake up on her own. Now she wakes up screaming from 16ish-18 months. Its so concerning to me because she has always been a happy girl. She had a bunch of molars come in around 16-17 months but now I dont know whats going on. What have you experienced? Can they be scared of the dark or have nightmares this early? I haven't got a baby monitor camera yet because they can be easily hacked into. What's your favorite baby monitor?

Do kids just start screaming when they dont want to go to bed at a certain age? I have a hard time letting her cry it out because I dont know if she needs me or if she is just trying to manipulate me into letting her stay up late.