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Parasomnias are abnormal events that happen while a person is asleep, including nightmares, night terrors and sleep-walking.

Sleep is divided up into rapid eye movement (REM) stages and non-REM. Parasomnias are most common during non-REM sleep and affect up to 30% of children at some stage.

Here are the most common types of parasomnias:

Types of parasomnias


Nightmares are vivid events experienced in the night with feelings of fear, terror or anxiety. If the person wakes up from a nightmare they may be able to describe the dream in detail. It can he hard to get back to sleep after having a nightmare. 

Causes include illness, anxiety, the loss of a loved one, or adverse reactions to a medication. If nightmares occur more than once a week, or prevent you from getting a good night's sleep over a prolonged period of time, it’s advisable to seek medical advice.

Sleep terrors/night terrors

A person experiencing a night terror or sleep terror abruptly awakes from sleep in a terrified state. The person may appear to be awake, but is confused and unable to communicate. They do not respond to voices and are difficult to wake up fully. Night terrors last about 15 minutes, after which time the person usually lies down and appears to fall back asleep. People who have sleep terrors usually don't remember the events the next morning. Night terrors are similar to nightmares, but night terrors usually occur within an hour or two of falling asleep.

People experiencing sleep terrors may pose dangers to themselves or others because of limb movements. Night terrors are fairly common in childhood and occur in about 5% of children, mostly between the ages of three and five. Children with sleep terrors will often also talk in their sleep and may sleepwalk. This sleep disorder, which may run in families, can also occur in adults. Strong emotional tension and the use of alcohol can increase the incidence of night terrors in adults.


Sleepwalking occurs when a person appears to be awake and is moving around but is actually asleep. They have no memory of their actions. Sleepwalking occurs most often during deep non-REM sleep (stages 3 and 4 sleep) early in the night and it can occur during REM sleep in the early morning. This disorder is most commonly seen in children between the ages of 8 and 12. However, sleepwalking can occur among younger children, the elderly and adults.

Sleepwalking appears to run in families. Contrary to what many people believe, it is not dangerous to wake a person who is sleepwalking. The sleepwalker may be simply confused or disoriented for a short time upon awakening. Although waking a sleepwalker is not dangerous, sleepwalking itself can be dangerous because the person is unaware of their surroundings and can bump into objects or fall down. With most children, it tends to stop as they enter their teen years.

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