Terror after dark

From sexsomnia to exploding head syndrome, Michelle O’connor investigates the most disturbing sleep disorders

Parasomnias are abnormal events or experiences associated with sleep, such as sleepwalking and night terrors. “They’re more common than people realise,” says Dr Ari Manuel, respiratory, sleep and ventilation consultant for Spire Healthcare and Liverpool University Hospitals NHS Foundation Trust.

“Unlike insomnia, the person is sound asleep and oblivious to their symptoms. So they only become aware of it when someone tells them.”

Even then, most people don’t seek help, “firstly, because they don’t understand the disorder and, secondly, because they don’t feel that doctors can help,” adds Dr Manuel.

Many parasomnias are thought to be caused by poor quality sleep, he explains. They may be a result of a primary sleep disorder, such as sleep apnoea, which is the interruption of breathing while sleeping, or narcolepsy which is a neurological condition that affects the brain’s control over sleep, resulting in sleep attacks during the day.

Non-rapid eye movement (NREM) parasomnias

These occur during the dreamless, deepest stage of the sleep cycle.

“NON-REM parasomnias occur because the part of the brain that deals with fight, flight and fright wakes while the parts of the brain that deal with planning, social context and logical thinking are fast asleep,” says Professor Matthew Walker, neurologist and expert in neurological sleep disorders.

Sleep deprivation, snoring, anxiety, taking certain medications that affect sleep, drinking alcohol before bed and restless legs syndrome increase the chances of NREM parasomnias.

Sleepwalking

Also known as somnambulism, this is more common in children and describes someone getting out of bed, walking around, and even performing complex tasks, and may be accompanied by sleep talking.

The sleepwalker may have their eyes open, speak, or otherwise appear awake, but will not recall the episode the following morning. Although generally harmless, it can be alarming for partners or housemates.

“There may be a genetic link as it can run in families,” explains Dr Manuel. “Some people make their way back to bed while others wake up.

However, if sleepwalkers are suddenly woken, they are likely to be shocked and disorientated so should be gently guided back to bed.”

Night terrors

These are not the same as nightmares, which occur in REM sleep, says Prof Walker. In around 80 per cent of cases there’s a family history, yet most children grow out of them by adulthood.

Night terrors can overlap with sleepwalking and, in these cases, people run to try to escape from something and look terrified. They can be inconsolable but have no memory of the experience.

Again, experts advise monitoring safety and guiding the sleeper back to bed once they calm down.

Confusional arousal

This is the sudden awakening from a deep sleep, says Dr Manuel, who likens it to surfacing from a deep-sea dive too quickly. The person is slow to respond, cannot think clearly, and might be frightened due to briefly misinterpreting things. For instance, an item of clothing may look like a snake.

“The person is disoriented but it tends to wear off quickly,” says Dr Manuel. “Sleep apnoea can be an underlying issue and if that is treated effectively, this deals with the confusional arousal.”

Sexsomnia

This is a rare condition that has only just been recognised as a parasomnia. It refers to sexual activity occurring when the subject is asleep, and unaware of their action. Like other non-rem

People run to try to escape something and look terrified, but can’t recall it

disorders, most people have no recollection in the morning. Many sexsomnia behaviours, such as masturbating, are harmless. But the condition has also been used as a defence in rape cases. Like other disorders, triggers include lack of sleep, exhaustion, drug and alcohol use, stress, anxiety, travel or simply sharing a bed with someone.

'Exploding head’ syndrome

This is when a person hears or feels a very loud noise, described as “a painless loud bang”, “a clash of cymbals” or even “a bomb exploding”, usually just before falling asleep or waking. The most likely explanation is that there is some kind of temporary blip in the nerve cells of the brain.

REM parasomnias

As the name suggests, during the REM sleep phase the eyes move very quickly from side to side, and this is when we typically dream, explains Prof Walker. REM parasomnias are less common and can be triggered by medication.

Sleep paralysis

Those who experience sleep paralysis describe being unable to move muscles while dropping off or waking up.

It’s thought to occur because the person is in “sleep mode” while the brain is active.

In many cases, there may also be visual, auditory and tactile hallucinations with the person seeing figures or animals, hearing footsteps or feeling pressure on their body or the bed. They may also feel as though they are floating or being lifted up.

False awakenings are also commonly reported – the person believes that they have awoken and that the episode is over when they are still asleep.

Episodes can last from a few seconds to several minutes and can end either spontaneously or because of an intense effort to break the paralysis or by the touch or voice of another person.

While many people experience sleep paralysis occasionally, around five to eight per cent of people are believed to experience regular episodes.

“Maintaining a regular sleep schedule and promoting good sleep hygiene are effective ways to manage sleep paralysis because it’s more likely to occur when someone has been sleep deprived or sleeping irregular hours,” says Dr Manuel.

REM behaviour disorder (RBD)

“Usually, our bodies are paralysed during dreams and we don’t act them out,” explains Professor Walker.

“In those with REM sleep behavioural disorders the mechanism in our brain that paralyses our body fails.”

So, if a person is dreaming of running, they will thrash their limbs as if they are running. Many people aren’t aware that they’re acting out their dreams until their bed partner notices it, or worse, ends up with bruises.

The disorder can occur at any age but is more likely to affect men over 50.

“In some people, REM sleep behavioural disorder may be associated with another neurological condition, and in particular, Parkinson’s,” adds Prof

Walker.

Treatment for parasomnias

Dr Manuel advocates taking a holistic approach. He says: “The most important thing is to try to prioritise quality sleep and remove stress by exploring lifestyle measures such as mindfulness, good nutrition and reducing alcohol consumption.”

But if the patient’s quality of life is affected they may need to attend a sleep clinic for assessment and be given medication or therapy to deal with the symptoms or the cause of the parasomnia, adds Prof Walker. “If sleep apnoea is thought to be the cause, we may recommend treatment with CPAP (continuous positive airway pressure).” REM disorders are more likely to require medication, such as clonazepam, he adds.

Usually our bodies are paralysed during dreams so we don’t act them out