Parasomnias and other Sleep Disorders

Sleep is not an ‘all or nothing’ phenomena. Parts of your brain can be asleep while others are awake. This means that if during slow wave sleep (SWS), often referred to as deep sleep, a particular part of the brain wakes up, a partial arousal, then it is possible to carry out the behaviour for which that part of the brain is responsible like walking or talking, without being conscious of it. The conscious part of the brain is still asleep.

Parasomnias are a group of sleep disorders that involve movement, seeing, hearing, or feeling things that aren’t there during sleep. They can often occur together.

Sleep walking, talking and REM behaviour disorders:

Sleep walking

Sleepwalking, also known as somnambulism, is a general term used to describe ‘normal’ events and tasks performed during the day that are performed sub-consciously during sleep. These can range from simply sitting up and looking around, going to the fridge for a drink of milk, going to post a letter or even getting in a car and driving. Somnambulism occurs during deep slow wave sleep (SWS) and is more likely to occur in the first third of the night in adults. It is not related to dreams.

Sleepwalking is reported to occur in approximately 1-2% of adults. There is a strong genetic link in the occurrence of sleep-walking, but anything that fragments sleep can precipitate these partial arousal’s; over-tiredness, stress, sleeping pills and alcohol to name a few.

Sleep talking

Sleep talking, also known as somniloquy, involves talking during sleep and is not physically or mentally harmful. The complexity of what is said can range from complete gibberish or mumbling to complicated dialogues or monologues that make sense. Anyone can experience sleep talking, but the condition is more common in males and children. Sleep-talkers are not aware of their speech so it may sound different from their normal speech. Sleep talking may be initiated by anything that disturbs or lightens sleep; stress, depression, fever, sleep deprivation, alcohol, not dissimilar to sleep walking.

REM Behaviour Disorder

REM behaviour disorder is a condition that is often confused with sleepwalking. As its name suggests REM behaviour disorder occurs during REM sleep (light, dream sleep) and not SWS like sleepwalking. In some people the paralysis associated with REM sleep does not always occur and subsequently they can physically act out their dreams. REM behaviour disorder can occur with abuse of drugs, medicines or alcohol or in people withdrawing from them. It can also be a precursor of Parkinson’s disease and is common in dementia.

Nightmares and Night Terrors:


Nightmares are essentially just bad, scary, horrific, frightening, disturbing dreams. The images and plots are often disturbing, with feelings, such as fear, anxiety, grief and anger. In just the same way that some movies are scary, some dreams can also be scary and our dreams are real to our mind and body. If you wake up during a nightmare you will remember some of the story and this can be frightening or unsettling. While for most of us our nightmares are just part of our rich dream life, for some, recurrent nightmares of traumatic events may be a symptom of Post-Traumatic Stress. Counselling should be sought if the nightmares are linked to a traumatic event.

Night Terrors

Unlike a nightmare, which is a bad or scary dream, night terrors are a parasomnia which occur during deep sleep (slow wave sleep), like sleep walking or sleep talking. During a night terror you can appear distressed or frightened and can exhibit movements that add to the impression that you are terrified of something. However, unlike a nightmare if you wake up during a night terror, you have no memory of what happened. As an observer to someone suffering from a night terror do not attempt to wake them, however distressed they may appear and however distressing it is for you. Night terrors are more common in children than adults.


One of the main causes of sleep impairment as we get older, besides those associated with natural ageing, is nocturia, the need to go to the bathroom multiple times during the night. Frequent nocturnal awakenings and the resultant sleep disturbance associated with nocturia can result in a severe disturbance of sleep leading to daytime fatigue and sleepiness together with a decrease in cognitive functioning and alertness.

While the sleep disturbance of the person with nocturia is of primary importance, it should also be recognised, that the sleep of the bed partner can also be greatly disturbed as a result of the sufferer having to get out of bed and go to the bathroom.

Approximately 10% of the general population over the age of 20 has nocturia and this increases with age. In the 50-59 age group, 58% of men and 66% of women experience nocturia.

Bruxism (Teeth grinding or clenching)

The repeated grinding of the teeth disrupts the sleep of both the sufferer and their bed partner. Bruxism affects about 1 in 12 people and is most common in people with sleep apnoea. It can cause severe damage to the teeth to such an extent that teeth are sometime lost and it can cause headaches and muscle aches. Lifestyles can also contribute to this disorder as heavy drinkers, smokers and coffee drinkers may be more prone than others. Individuals should look after their well-being as modifications to diet may help alleviate symptoms. In severe cases the use of a plastic splint or tooth guard to protect and preserve the teeth may be necessary during the night.

Restless Leg Syndrome (RLS)

RLS causes you to have an irresistible urge to move your legs.  You may feel sensations of pain, tingling, itching, or prickling, (one person described it as ‘ants crawling under the skin’), which is only relieved by moving the legs. However, the sensations return when the legs are still again. RLS can occur if you sit immobile in a chair for an extended period of time but it is most likely to occur when they lay down in bed, making sleep difficult.

RLS can be a symptom of anaemia, or a result of, iron deficiency or folic acid deficiency. Some pregnant women suffer from the condition, especially in the last trimester of pregnancy.

Symptoms may also be due to other underlying conditions such as diabetes, rheumatoid arthritis, neurological diseases, or Parkinson’s disease. RLS may be relieved by ensuring your diet contains adequate amounts of iron, folic acid and minerals such as calcium, potassium and magnesium. Walking, stretching and yoga may also help to relieve the symptoms. If you suspect RLS you should see your Doctor.

Periodic Limb Movement Disorder (PLMD)

Periodic Limb Movement disorder is where the you repeatedly make kicking and jerking movements during sleep, most commonly, with your legs or less frequently your arms. Although the you are unaware of what is happening, the repeated movements can disturb your sleep causing you to experience daytime sleepiness. You are usually unaware that this occurs and more often it is your bed partner that notices this behaviour. Women are more likely to suffer from the condition than men and it may often be a result of too much caffeine, stress and mental health problems.

Should you or your partner suspect PLMD we would encourage a visit to your Doctor.

Sleep Paralysis

Sleep paralysis is a common condition where people wake up during the night and feel that they cannot move and/or feel a heavy pressure on their chest making it difficult to breath. Essentially when you are dreaming you are usually paralysed so that you are unable to act out your dreams, however sometimes when you wake up from a dream this paralysis may persist for a number of seconds making you feel that you cannot move or breathe.


Narcolepsy is a very rare condition which causes you to have an uncontrollable urge to fall asleep whatever you are doing, even in the middle of a sentence. It’s thought to be caused by the faulty control of the sleep/wake cycle, in particular REM sleep, and there is some evidence that it might be linked to a lack of orexin, a brain chemical that promotes alertness although there is also evidence that it is a genetic predisposition.

Other than the uncontrollable sleep attacks, which of course could be extremely dangerous in particular situations, symptoms include insomnia and excessive daytime sleepiness. Narcolepsy is sometimes linked with cataplexy where there is a loss of muscle tone during periods of high excitement. Narcolepsy usually starts to occur in young adulthood. Non-pharmacological treatment is based around lifestyle changes and coping strategies.

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