Not waking up a sleepwalker is more harmful than waking one up!

Sleepwalking is more common in children than adults and more likely to occur when one is sleep deprived. Sleepwalking happens when one is in a deep sleep and therefore they are more difficult to awake and most likely they will not remember sleepwalking. 

It is a misconception, though, that it is important to not wake up a sleepwalker. In fact, it could be quite dangerous if you don’t wake them up. Sleepwalkers do things from sitting up in bed and look around to walking out of their home and driving their car for long distances. Some medications and sedatives can increase the onset of sleepwalking. 

There is a higher prevalence of sleep walking in children who wet the bed than those that do not. There isn’t a cure for sleepwalking, though. Improving one’s sleeping habits and patterns can eliminate the problem of sleepwalking. Eliminating alcohol and certain medications can also lessen the likelihood that sleepwalking with continue. 

(Source)