Nearly every child experiences bad dreams, but according to a recent study frequent nightmares — or bouts of night terrors — may be an early warning sign of psychotic disorders.

Researchers from the University of Warwick in the United Kingdom found that children who regularly suffer from nightmares before the age of 12 were three and a half times more likely to develop delusions, hallucinations, and other psychotic episodes. Those who suffered from night terrors had double the risk of such problems, according to the study.

Night terrors – screaming and thrashing limbs while asleep – are far more severe than nightmares and occur during deep sleep.  Nightmares occur during the REM stage of sleep and are far more common.

For the study, researchers examined data from the Avon Longitudinal Study of Parents and Children (ALSPAC), based in England. The group included more than 6,700 children between two and nine years old, and involved multiple assessments, including an assessment at age 12 for any signs of mental illness.

After extensive research scientists found a strong link between nightmares and night terrors in childhood and future mental illness in adolescence.  According to result findings, children between the ages of two and nine who experienced frequent nightmares are more than three times more prone to having psychotic experiences in adolescence.  Those who suffer regular bouts of night terrors have twice as much risk of having issues with mental health during teenage years.

“We certainly don’t want to worry parents with this news; three in every four children experience nightmares at this young age,” Dieter Wolke, a lead researcher, said in a statement. “However, nightmares over a prolonged period or bouts of night terrors that persist into adolescence can be an early indicator of something more significant in later life.”

:”This is a very important study because anything that we can do to promote early identification of signs of mental illness is vital to help the thousands of children that suffer,” said Lucie Russell, the director of campaigns at YoungMinds. “Early intervention is crucial to help avoid children suffering entrenched mental illness when they reach adulthood.”