New research 'closer to finding the cause of narcolepsy'

New genetic research in Japan could give some clues to what causes the sleep condition of narcolepsy.

The illness causes extreme daytime tiredness, when sufferers have to lie down in bed, or unexpected "sleep attacks" and sudden muscle weakness, known as cataplexy.

It is thought by researchers at the University of Tokyo that a variant in a gene used to regulate sleep could be the cause.

After testing hundreds of volunteers, it was found that Japanese people with the variant had a 79 per cent higher chance of suffering from narcolepsy.

The authors of the research wrote: "We hope that the discovery of the present susceptibility gene(s) might contribute to the establishment of novel therapeutic approaches."

Another theory by scientists is that the condition could be caused by lower levels of hypocretin in some people, which sends signals to the brain about sleeping and waking up.

The Narcolepsy Association UK says that around five in every 10,000 people in Europe have the illness and advises sufferers to try and go to bed at the same time every night to establish a routine.