Parasomnias are a group of sleep disorders characterized by unusual movement, perception, emotion, behavior 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. Disorders that affect the REM sleep are referred to as REM parasomnias.

REM sleep behavior disorder

This is the most common form of REM parasomnia and refers to when the muscles become weak, meaning a person is vulnerable to injury as they try to act out events occurring in their dreams. This can lead to fracture, bruising or wounds to the person with the disorder or those around them. Patients sometimes take protective measures such as tying themselves to the bed or using pillow barricades. This disorder generally affects males, with 90% of cases affecting men aged older than 50 years.

The main features of this disorder are listed below:

• Male gender
• Average age of onset is 50 to 65 years
• Screaming and shouting that may be linked to dreaming
• Uncontrolled movements that lead to injury
• The condition is sometimes associated with neurodegenerative disease.

In over half (55%) of acute cases, the cause of this disorder is not known and the remainder are associated with alcohol. The cause of chronic cases is usually unknown but research has shown an increasing association with neurodegenerative diseases such as Parkinson’s disease, dementia and multiple system atrophy.

Recurrent isolates sleep paralysis

Here, the affected individual cannot carry out voluntary movements as they are falling asleep or waking from sleep.

Catathrenia

Here, the affected individual holds their breath and then groans on breathing out. Unlike snoring, the groan is produced as the person exhales. Although it usually goes unnoticed by the affected individual, the problem can be very disruptive for a person sharing the bed or bedroom.

Partners generally report that they hear the affected individual breath in deeply, hold their breath and then slowly exhale while producing a long groan or high-pitched squeaking sound.