The study by the University of Warwick and published in the journal SLEEP, shows that children reporting frequent nightmares before the age of 12 were 3 and a half times more likely to suffer from psychotic experiences in early adolescence.
A high number of 'night terrors' also increased the risk of such problems, including hallucinations, interrupted thoughts or delusions. Younger children, between 2 and 9 years old, who had persistent nightmares reported by parents had up to 1 and a half times increased risk of developing psychotic experiences.
Nightmares are considered to be commonplace in young children with incidence reducing as they grow older. They occur in the second half of the night during REM (rapid eye movement) sleep. Those who have experienced them will be familiar with the sensation of waking suddenly with a sense of fear, worry and possible palpitations.
Night terrors, a sleep disorder, differ from nightmares and occur during deep sleep (non-REM) cycles in the first half of the night. A night terror bout is often signified by a loud scream and the individual sitting upright in a panicked state, though unaware of any of the involuntary action. Children wake up in the morning unaware of their activity throughout the night.
Study lead, Professor Dieter Wolke, said: “We certainly don’t want to worry parents with this news; 3 in every 4 children experience nightmares at this young age. 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.”
Experiencing psychotic episodes
The cohort was assessed 6 times between the ages of 2 and 9 and the likelihood of experiencing psychotic episodes in adolescence increased with the incidence of nightmares during that age.
Those who only reported one period of recurrent nightmares saw a 16% rise, whereas those who reported three or more sustained periods of nightmares throughout the study saw a 56% increase in risk.
By the age of 12, 24.4% of children in the study reported having suffered from nightmares in the previous 6 months, with 9.3% experiencing episodes of night terrors during the same period.
Lucie Russell, director of campaigns at YoungMinds, added: “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. Early intervention is crucial to help avoid children suffering entrenched mental illness when they reach adulthood.”
Further reading: Sleep and mental health feature
Dr Helen Fisher, of King’s College London, concluded: "The best advice is to try to maintain a lifestyle that promotes healthy sleep hygiene for your child, by creating an environment that allows for the best possible quality of sleep.
"Diet is a key part of this, such as avoiding sugary drinks before bed, but at that young age we’d always recommend removing any affecting stimuli from the bedroom – be it television, video games or otherwise. That’s the most practical change you can make."