Violent sleep disorder: Why am I violent in my sleep?

Imagine waking up from a nightmare, your relief quickly disappearing as you realise the attacker you’d been fending off was in fact your sleeping partner, now awake and very upset.

This is what can happen to people who have REM sleep behaviour disorder (RBD).

Most dreams, good or bad, take place during REM sleep when muscles are limp. This muscle atonia prevents people from moving around and hurting themselves or others while dreaming. In RBD, the muscles stay tonic, which means that people can act out their dreams.

These dreams are vivid and typically unpleasant, action-filled and violent. Donald Dorff—the first person to be diagnosed with RBD over 40 years ago, aptly described them as “violent moving nightmares”.

The combination of nightmares and REM sleep without atonia is potentially dangerous. For Mr Dorff, it resulted in injury after he threw himself at furniture while dreaming he was playing American football.

“The person will not recall this event the next day unless they wake up during their RBD episode. They'll say they were in a dream, that they were pushing someone who was attacking them, but actually, they were pushing their bed partner,” explains Professor Michele Hu, a professor of neuroscience and consultant neurologist at Oxford University Hospitals.

“The bed partner can have a black eye, they can get kicked, and be pushed out of bed.”

When they remember their nightmares, patients with RBD often say that they were being attacked or chased by unfamiliar people or animals, but not all the episodes are unpleasant. 

“Sometimes the dreams are vivid and quite pleasurable and people might just talk or laugh a bit, but it can be loud,” says Professor Hu.

As many as 100 million people could be living with RBD worldwide, but it can go unnoticed until a bed partner/roommate complains about the night-time behaviours, or the patient wakes up with unexplained bruises.

RBD is more frequently reported in men over 50. Women are less likely to have violent dream-enacting behaviours and are, therefore, less likely to be diagnosed.

In younger people, RBD is associated with antidepressant use and is very common in those with narcolepsy.

Many don't realise they are violent during sleep until their sleep partner complains

Dream-enacting behaviours are common and not always due to RBD. Healthy people can act out their dreams, especially when experiencing stress.

Dream-enacting also happens in other sleep disorders, such as sleepwalking, nocturnal terrors, sleep apnoea, nocturnal epilepsy, or in mental health conditions like post-traumatic stress disorder.

This makes RBD diagnosis challenging. It is only possible to confirm diagnosis after an overnight sleep study with a polysomnogram that monitors brain activity, eye movements, and muscle tone during REM sleep.

RBD questionnaires, such as the one developed by the Mayo Sleep Clinic in the US, can help GPs with initial diagnosis.

This questionnaire asks the bed partner if they have ever seen the patient appear to “act out his/her dreams” while sleeping (for example, punched or flailed arms in the air, shouted or screamed). A “yes” warrants a visit with a GP and a potential referral to a sleep clinic.

It is unclear what causes RBD, but it is likely related to disrupted neural pathways in the brainstem.

As a neurologist who specialises in Parkinson’s disease, Professor Hu is particularly interested in RBD. Within 20 years of diagnosis, over 80 per cent of patients will develop Parkinson’s disease or another neurodegenerative disorder, such as dementia with Lewy bodies.

Although such a diagnosis can be overwhelming, it also provides patients and researchers with a precious window of opportunity. Professor Hu is conducting long-term studies in patients with RBD to get a better understanding of how Parkinson’s disease develops.

RBD patients are also included in biomarker studies: a biomarker for Parkinson’s disease would increase the success of clinical trials into neuroprotective and disease-modifying treatments and potentially revolutionise treatment.

RBD could be an early sign of Parkinson's, which may help patients predict and prevent neural degeneration

Sleep doctors disagree about whether to inform patients with RBD about their risk of developing Parkinson’s disease.

Professor Hu believes patients should be told, because their diagnosis gives them an opportunity to contribute to research efforts and to improve their brain health through lifestyle changes.

For instance, maintaining healthy blood pressure, weight and cholesterol levels can help reduce vascular risk factors, which is crucial for maintaining brain health.

Regular exercise is also important because it is a proven neuroprotective intervention for early Parkinson’s disease. Studies show that walking about 10,000 steps a day as quickly as possible significantly reduces the risk of developing dementia.

Over the short-term, patients with RBD need to make their sleeping environment as safe as possible. This can mean removing or padding furniture, sleeping in a wide bed, lowering the mattress, or cushioning the floor in case of falls. Bed partners may need to sleep in separate beds.

Pharmacological treatments are available and include melatonin and clonazepam. Both these drugs decrease the frequency and intensity of RBD episodes.

Read more: The science of dreaming

Read more: Is a perfect night's sleep possible?

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