Non-rapid eye movement (NREM) sleep arousal disorders refer to the repeated episodes of incomplete awakening from sleep that include behaviors such as sleepwalking and sleep terrors. These episodes usually happen during the first third of the night and people will be confused and disoriented if awakened during an episode. People with this condition have no memory of their dreams or sleep behavior in the morning.
NREM sleep arousal disorders occur most commonly in childhood and happen less often with advancing age. Isolated or infrequent NREM sleep arousal disorders are common, with 10 to 30 percent of children having had at least one episode of sleepwalking; 2 to 3 percent of children sleepwalk often. The prevalence of sleepwalking episodes among adults is in the range of 1 to 7 percent, but far fewer adults have episodes on a regular basis. Sleepwalking occurs more often in females during childhood and more often in males during adulthood.
People experiencing NREM sleep arousal are considered partially asleep and partially awake during an episode. Episodes are usually short, lasting one to 10 minutes, but can last up to an hour. Sleepwalking and sleep terrors commonly occur during the episode.
Sleepwalking and sleep terrors are partial or incomplete awakenings from deep sleep. Sleep terrors refer to episodes in which a person is suddenly aroused from sleep by an intense fear. Episodes usually begin with a panicky scream and are accompanied by the physical signs of fear, such as fast breathing and sweating. It is difficult to awaken or comfort a person while they are experiencing an episode of sleep terror. They will typically not awaken fully, but will return to sleep and not remember the episode the next morning.
Sleepwalking is a behavior in which a person rises from their bed during sleep and walks around. They have a blank expression on their face, are mostly unresponsive to communication from others, and are difficult to awaken. Most episodes of sleepwalking involve behaviors that are routine and not complex, such as using the bathroom, eating, and talking. People have been reported to engage in more complex behaviors, however, such as unlocking doors and driving an automobile. There are also two “specialized” types of sleepwalking: sleep-related eating behaviors and sleep-related sexual behavior (sexsomnia). These refer to episodes in which a person engages in unwanted eating during the night with no memory of it in the morning, or a person engages in sexual activity (masturbation, groping, sexual intercourse) without conscious awareness.
NREM sleep behavior disorder has a genetic component, with some people who sleepwalk having a family history for sleepwalking or sleep terrors. There are several other risk factors that can increase the likelihood of episodes, such as sedative use, sleep deprivation, sleep schedule disruptions, exhaustion, and physical or emotional stress.
Treatment for NREM sleep behavior disorder depends on the severity of the condition. Most children will grow out of this sleep disorder as they grow, so while it may be frightening for their parents, the child will not be aware of their nighttime behavior as it’s happening and will not be in danger. Creating good habits around sleep may help reduce the frequency of episodes, such as getting enough sleep each night. Alcohol use should also be reduced among adults with this condition.
If episodes are frequent or create a dangerous situation for the person or their bed partner, changes should be made in the sleep environment to promote safety. Such changes can include:
- Padding the floor around the bed with a mattress or pillows
- Padding corners of nearby furniture
- Window protection
- Removing dangerous objects, such as guns or sharp objects, from bedroom area
- Locking doors and windows
- Sleeping in a separate room from the bed partner until symptoms are under control
In severe cases, medication can also be prescribed to reduce the frequency of episodes.