There are two types of sleep - the Slow Wave Sleep or non-rapid eye movement (NREM) sleep and the Rapid Eye Movement (REM) sleep. NREM is a deep, restful type of sleep occuring during the first hour. It is divided into 4 stages and is interrupted periodically by REM sleep. REM sleep sets in 80-100 minutes after sleep onset. It lasts for 5 to 30 minutes and recurs every 90 minutes. REM sleep is not so restful and the eyes undergo rapid movement. In a normal sleep pattern, there is a cycling throughout the night between wakefulness, NREM, and REM sleep. In children, deepest sleep takes place 15 minutes after sleep onset. Sleep walking, also known as somnambulism, is characterized by simply sitting up,quiet walking, to running around the room with the eyes open. The person may also perform complex activities like cleaning the house, moving furnitures, changing clothes, and other similar activities.The episode usually lasts for a few seconds to an hour or more. Although the person is asleep, he tends to avoid obstacles but the incident is not remembered on waking up.It occurs most often during stage 3 or 4 NREM sleep early in the night and usually recurs during REM sleep in the morning. It is common in middle childhood and pre-adolescence. Peak incidence is seen in children 11 to 12 years old. The cause is unknown. It is usually associated to fatigue and anxiety in children to complex medical conditions in adults. |
