Children who reported experiencing frequent nightmares between 2.5 and 9 years of age were significantly more likely to report psychotic experiences at age 12, regardless of sex, family adversity, emotional or behavioral problems, IQ or potential neurological problems, according to research published in the journal Sleep.
Fisher, H., Tanya Lereya, S., Thompson, A., Lewis, G., Zammit, S., Wolke, D., Childhood Parasomnias and Psychotic Experiences at Age 12 Years in a United Kingdom Birth Cohort. Sleep. 2014; 37(3):475-482 doi.org/10.5665/sleep.3478
Of further interest:
Childhood nightmares may point to looming health issues (BBC Health)
Childhood nightmares could foreshadow mental health issues (Daily Dose)
Nightmares Can Be Early Sign of Mental Illness: Study (Newsmax Health)
Childhood Nightmares May Lead to Psychosis, Say Scientists (International Business Times)