Why sleeping for too long raises risk of nightmares

IN our hectic lives, the chance to have a lie-in is a dream come true for many of us.

But sleeping for too long can actually cause nightmares, research suggests.

More than nine hours of shuteye doubles your risk of having a bad dream compared to getting six hours, an Oxford University study found.

Co-author Dr Bryony Sheaves, a research clinical psychologist at Oxford’s Sleep and Circadian Neuroscience Institute, explained this is because nightmares occur during the rapid eye movement (REM) stage – a type of sleep that occurs in intervals during the night – and so if you spend longer asleep you will go through more stages of REM. The scientists said seven to nine hours is the optimum amount of sleep.

On the popular theory eating cheese before bed can give you bad dreams, Dr Sheaves said: ‘Rather boringly, no study I have read has actually tested this. But I think it shows people are fascinated about why we have nightmares. Our research has built on this fascination.’

The team questioned 846 people aged 18 to 77 and found 45 per cent had suffered at least one nightmare in the previous fortnight.

To see what affects frequency of bad dreams, they looked at sleep, alcohol consumption, exercise levels, worry, paranoia and hallucinations.

Sleep duration was the second biggest risk factor after worrying. It is believed the repetitive thoughts triggered by anxiety ‘feed’ negative dream content. Alcohol and a lack of exercise were found to have no effect on nightmares, the study, published in the journal Social Psychiatry and Psychiatric Epidemiology, found.