In its broadest term, parasomnias are a type of unwanted behavioural, physiological or experiential event that happens while a person is asleep. 

There are many different types of parasomnias, each of which happen at distinctive parts of the sleep cycle.

Parasomnias are a very common thing

Do you know anybody who has ever sleepwalked, or have you ever had a nightmare? Those are examples of parasomnias.

Historically people believed that parasomnias were a sign of underlying psychological issues, yet this has recently been dismissed; they are simply phenomena that happen when the brain transitions between different stages of sleep, and between the states of sleep and wakefulness.

The sleep cycle

The sleep cycle consists of two different types of sleep: rapid eye movement (REM) and non-rapid eye movement (NREM).

During sleep you switch between these two states many times during the night, with different amounts of each at different times (for example, you’ll tend to have more NREM sleep at the beginning of a night and more REM at the end of the night).

There are also certain stages of NREM, stages 1,2,3 and 4, each being a deeper level of sleep.

A typical sleep cycle has all of these stages and lasts for about 90 minutes.

If you are woken up in the middle of REM sleep you are more likely to wake up alert and remembering your dreams. If you are woken up in NREM, you are more likely to wake up sluggish and not really remember what you were dreaming about.

The same is true of parasomnias; you are more likely to remember what was going on and what you were dreaming about in different phases of sleep.

Types of parasomnia

There are two main types of parasomnia – NREM and REM.

parasomnia_2NREM parasomnias

Also referred to as ‘disorders of arousal’ and ‘sleep-wake transition disorders’. If you have ever pressed snooze on the alarm clock and get into a pattern of walking then sleeping, this is an example of a mild confusion parasomnia called ‘sleep drunkenness’ (I think we have all done this at some point!)

Arousal parasomnias are when people do things when they are partially awake and partially asleep. 

Sleepwalking is a common example and sleep terrors are another.

On the whole younger children tend to get this more than adults due to children generally being in a longer state of NREM stages 3+4 (deep sleep). Some drugs that cause deep sleep can also increase the likelihood of getting these, as are things that disrupt the normal sleep pattern, such as shift work.

REM parasomnias

are mainly limited to a condition called ‘REM-sleep behaviour disorder’.

Normally during REM sleep, the brain coordinates the body so that you are paralysed – you cannot move.

In REM-sleep behaviour disorder the message from the brain that tells your body not to move isn’t working as it should, meaning that the person starts to act out their dreams.

People tend to mostly act out more threatening dreams which can lead to distressing situations for both the sleeper and their partners.

With this type of parasomnia, if the sleeper wakes up during the episode, they will generally be able to describe in detail what they were dreaming about, and will be in a higher state of arousal (as in, they will feel alert rather than drowsy).

Night terrors and nightmares

Nightmares are also a type of parasomnia, but there are specific differences between night terrors and nightmares.

Nightmares never evolve into sleepwalking, while some night terrors do.

People who have nightmares do not have the feeling of confusion of disorientation when they wake up; they can usually able to recall the dream quite well.

If you are at all worried about parasomnias please consult your GP.

How to decrease parasomnia

There are a couple of things that you can do in your everyday life that may decrease the likelihood/number of parasomnias.

1. Decrease stress levels

Note: some antidepressants actually increase the likelihood and occurrences of a parasomnia. If this is the case, please consult your GP.

2. Get enough sleep (preferably uninterrupted)

3. Eat a balanced, healthy diet

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