Adults who sleepwalk are more likely to have a specific genetic variant of part of their immune system than those who do not. Sleepwalking in adults is quite different from childhood sleepwalking. It's more likely to lead to injury or violent behaviour, and those affected often have other health problems, like sleep apnoea. A study of 60 adult sleepwalkers in Bern, Switzerland, shows an interesting genetic variation in these patients.
Genetic testing for a part of the immune system called HLA was performed in a subgroup of these sleepwalkers. Half of them were carrying a specific genetic variant of HLA, compared to just 20 per cent in a control group of non-sleepwalker. It's not yet clear just how this immune variant affects the body's sleep cycles. But it's also interesting to note that many of these patients also suffer from REM (rapid eye movement) sleep disorder - where their muscles are not paralysed (as they usually are) during dreaming. It may be that treating some of the accompanying disorders, such as REM disorder or sleep apnoea, may help alleviate adult sleepwalking.