Having a biological marker gives extra confidence to doctors to have an objective test

Professor Chris Idzikowski, sleep expert

The researchers identified a particular form of the genes which they suspected would make people susceptible to sleepwalking.

They found it in 50% of the patients tested, but in only 24% of healthy people tested to provide a comparison.

Adult sleepwalking is associated with potentially dangerous activities, researchers told the American Academy of Neurology's annual meeting in Denver, USA.

In this study, 32% of patients reported violent incidents occurring while sleepwalking and 19% reported injuries occurring while sleepwalking.

Dr Claudio Bassetti from the University of Switzerland in Zurich, said: "Normally, REM sleep is accompanied physiologically by paralysis, which protects us from acting out our dreams.

"In people with REM sleep behaviour disorder, this paralysis doesn't occur normally."

Added health problems

In the study, 25% of the patients had increased muscle activity during REM sleep.

Sleepwalking had been occurring since childhood in 58% of the patients.

For 24% of the patients, other family members were also sleepwalkers.

Many of the patients also had other health issues - 23% had mental health problems and 7% abused alcohol.

Of the 53 patients tested, 11 had sleep apnoea.

Dr Bassetti said: "Treating these other issues may also help improve or resolve the sleepwalking."

Director of the Sleep Assessment Advisory Service in London, Professor Chris Idzikowski, said sleepwalking is very difficult to treat.

However, he suggests highlighting the presence of a genetic marker may help doctors diagnose the condition.

He said: "Having a biological marker gives extra confidence to doctors to have an objective test.

"This looks, potentially, to be a useful marker to use to aid treatment."

Dr Bassetti said he could not draw any conclusions from the research on whether sleepwalking was due to faults in the immune system.

However, Professor Idzikowski said there was a possibility that sleepwalking could be a variation of an auto immune disorder, due to the genetic marker.

He said further research would need to be carried out to establish this.