Why do I sleepwalk?

Felicity Bedford has trying to find out the answer to this one with Dr Ian Smith from the sleep clinic at Papworth Hospital...

Felicity - I don't think I ever sleepwalk but I wonder how many people don't know that they have strange nocturnal behavior. I spoke to Dr. Ian Smith from Papworth hospital's sleep clinic who explained how a snooze can lead to a late night stroll.

Ian - Sleepwalking is almost normal in children; up to a fifth of children will do it at some stage, usually with no important consequences. Sleepwalking starts in deep sleep, and this is deeper in children than in adults. This deep sleep stage is the most refreshing and seems to be important to brain repair and memory sorting, but memory itself is switched off during deep sleep. And so one feature of sleepwalking is that the walker usually has no recollection of what's happened. Some stimulus - a noise, being jogged, an irregular patch of breathing - jolts the sleeper out of deep sleep into a mixed wake-sleep state. Most people would just fall back to sleep, but those prone to sleepwalking will get up and start roaming without waking completely. Typically, the walker will have their eyes open but will not fully interact with other people. They'll often navigate obstacles skillfully but may not recognise dangers: they might for example try to climb out of a window; usually an episode lasts just a few minutes and then the walker returns to bed.

Felicity - Is there any particular reason you might be prone to wandering around the house like a zombie in the dead of night? 

Ian - Sleepwalking runs in families, and in some people a marker has been found in the genetic code which is strongly associated with the condition. It is not advisable to try and wake a sleep walker as they may be confused and aggressive.

Felicity - That's good to know, but if sleepwalking is in your genes, is there anything you can do to prevent it?

Ian - In managing a sleep walker, we would look to reduce triggers which include irregular sleep habits, stress, alcohol, some antidepressants, and sleep apnoea - that's interrupted breathing during sleep. Occasionally, people put themselves and others at risk during sleep walking and medication can reduce the frequency of episodes. Simple precautions for safety include locking upstairs windows, removing sharp and fragile objects from the bedroom. In people with disruptive sleep walking we would recommend referral to a specialist sleep clinic.

Felicity - Thanks Ian. I hope that helps Sterling, and that answer means you can sleep easy now. Our next question is from James...

James - So what are the bags you get under your eyes when you're tired? One thought: they're facial markings that have evolved to warn people away from crabby, bad sleepers!