Sleepwalking, formally known as somnambulism, is a sleeping disturbance that occurs in deepest part of non-rapid eye movement (NREM) sleep. It usually occurs within 1-2 hours of falling asleep. It's thought to be a hereditary condition. It's triggered by sleep deprivation, stress, infection with high temperature, consumption of too much alcohol, certain sedatives and abrupt waking from deep sleep.