Parasomnias are a group of sleep disorders characterized by unusual movement, perception, emotion, behaviour and dreams while a person is between the different phases of sleep or awaking from a sleep.

Generally, these problems occur while the patient is partially aroused as they transit from being awake into non-rapid eye movement (NREM) sleep or into rapid eye movement (REM) sleep. When the disorder affects NREM sleep, it is referred to as NREM parasomnia.

NREM parasomnias

The International Classification of Sleep Disorders 2nd Edition (ICSD-II) classifies NREM parasomnias into three main types:

• Confusional arousals
• Sleepwalking
• Night terrors

Confusional arousal

This refers to when a person becomes confused as they are waking up, perhaps partially remaining in a sleep state still with their eyes open and looking around. In children, confusional arousal often causes a lot of moaning, movement and sometimes inconsolable crying.

Sleepwalking

Sleepwalking can refer to simply sitting up and looking awake when you are not or actually leaving the bed and walking around and moving items, for example. The person may also talk or appear to be having an argument, even though the words may not make sense. In adults, sleepwalking is often associated with the use of medication, alcohol, sedatives and mental disorders. Anxiety and fatigue are also associated with the disorder.

Sleep terrors

Also called night terrors, this is an arousal disorder that causes panic and loud screaming and even bodily harm if the person gets up and runs about. No attempt should be made to comfort the person as this can intensify the terror. People who experience sleep terrors usually forget the experience afterwards, although they may have a partial memory of it.