Question: why do people sleep walk

Tim Downing answered on 18 Nov 2012:

Hi Jellytots,

People sleep walk because we are all able to do routine things (like walking) using our subconscious only. Even we are asleep, our level of consciousness varies – sometimes we are sleeping deeply or lightly, and this ebbs and flows as phases of about 90 mins during the night. During light sleep phases, we tend to move around more, like most of us do in our bed. So sleep walk is an extension of this, just the moving around on the bed has switched to getting out of it!

You can understand the variation in consciousness from when you are dozing, or waking up or falling asleep. We still manage to breathe while asleep so this is one of a range of functions that is automatic. For sleep walkers, wandering around has become an automatic behaviour.

One interesting aspect of sleep walking is that it tends to occur at the start of the night during “slow wave” deep sleep phases rather than light sleep. This is why sleep walkers don’t wake up easily during their odd behaviour. The origins of sleep walking are not clear: though it is genetic in part, other factors can affect it. For example, if you don’t get much sleep the night before, your amount of slow wave sleep will increase and give you more time in which to go sleep walking.

Tim