The study, published in the journal SLEEP, suggests that children reporting frequent nightmares at the age of 12 were 3.5 times more likely to suffer from psychotic experiences in early adolescence. Similarly, experiencing night terrors doubled the risk of such problems, including hallucinations, interrupted thoughts or delusions. Younger children, between two and nine years old, who had persistent nightmares reported by parents had up to 1.5 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 sleep 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. The thrashing of limbs and rapid body movements are witnessed in more extreme cases. Children wake up in the morning unaware of their activity throughout the night.
Dr Helen Fisher, co-author of the study from the MRC Social, Genetic and Developmental Psychiatry (SGDP) Centre at the Institute of Psychiatry at King’s says: “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.”
Professor Dieter Wolke, from Warwick, says: “We certainly don’t want to worry parents with this news; three in every four 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.”
Nearly 7,000 children from the Avon Longitudinal Study of Parents and Children (ALSPAC) were included in the study. The mothers’ provided information on nightmares on six occasions when their children were aged two to nine. The children were then interviewed at the age of 12 about their nightmare and psychotic experiences.
The likelihood of experiencing psychotic experiences in adolescence increased with the incidence of nightmares. 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.
In contrast, problems with falling asleep or night waking (insomnia) had no relationship to later psychotic experiences.
By the age of twelve, around one in four (24.4%) of children in the study reported having suffered from nightmares in the previous six months, with fewer than one in ten (9.3%) experiencing episodes of night terrors during the same period.
ALSPAC is supported by the Medical Research Council (MRC), Wellcome Trust and the University of Bristol. Funding was also provided by the MRC, the Economic and Social Research Council (ESRC) and the National Assembly for Wales.
Paper reference: Fisher HL et al. ‘Childhood parasomnias and psychotic experiences at age 12 years in a United Kingdom birth cohort’ published in SLEEP doi: 10.5665/sleep.3478
King’s College Londo