A horde of popular superstition has amassed around somnambulism. It has long been held that you risk violence if you wake up sleepwalkers. This is simply not true, although another parasomnia, REM movement disorder, can lead to violence as the afflicted person acts out dreams. Somnambulists will often be confused or disoriented when awoken, however, so often its best not to wake them. Instead, gently talk to them and try to get them to return to bed without waking.
Another popular legend holds that somnambulists cannot fall or injure themselves while sleepwalking. This too, is not true. Falls and injuries are actually fairly common.