Children who experience persistent nightmares may be more likely to suffer psychotic symptoms in their late teens, a new study suggests.

Psychosis refers to a mental state in which a person is detached from reality and experiences a number of abnormal symptoms such as hallucinations, delusions and incoherent thoughts.

The UK study involved over 4,000 young people. Parents reported on the children's experiences of nightmares between the ages of two and nine years. The children were then interviewed about nightmares, night terrors and sleepwalking when they were 12 years old and 18 years old.

The researchers found that those who persistently suffered with nightmares between the ages of two and nine, and at the age of 12, were significantly more likely to experience suspected or definite psychotic symptoms at the age of 18 years.

"The presence of anxiety and depressive symptoms as confounding factors in those with sleep disturbance could potentially explain the findings. Experience of stressful events has also been related to the development of both nightmares and psychotic symptoms in late childhood and may be important," commented the study's lead author, Dr Andrew Thompson, of the University of Warwick.

He suggested that these findings could have implications for the way that nightmares in children are viewed by both parents and professionals.

"It is likely that in some individuals, nightmares and night terrors have little significance to later psychopathology. However, in individuals with additional risks such as a family psychiatric history or a past exposure to trauma by adults or peers, such sleep problems may have greater significance and may also highlight other unnoticed psychopathology or trauma," Dr Thompson said.

He called for more research in this area, but added that these findings suggest that persistent nightmares in children may be a risk factor for the development of psychosis later on.

Details of these findings are published in the British Journal of Psychiatry.