Nightmares could be a sign of mental health issues, reports CNN.

If bad dreams start frequenting your nights, it could be a sign of health problems. An estimated 2% to 8% of adults can’t get rest because terrifying dreams wreak havoc on their sleeping patterns.

In particular, nightmares can be an indicator of mental health problems, such as anxiety, post-traumatic stress disorder and depression.

A phenomenon called REM sleep behavior disorder, in which a person acts out aggressive dreams by screaming, moving around or jumping out of bed, could also predict neurological diseases like Parkinson’s, according to research.