They reported having more negative dream themes such as frightening dreams, or ones in which sad or angry emotions surfaced. (sciencedaily.com)
Nightmares are frightening dreams associated with REM sleep, and they are more likely to occur after a child has been sleeping for several hours. (parentingscience.com)
If your child suffers from frightening dreams or nighttime screaming episodes, you might also want to check out this article on nightmares and night terrors. (parentingscience.com)