What is RBD?

RBD stands for “REM sleep behaviour disorder”, causing affected people to act out their dreams instead of lying completely still during the REM-phase of sleep. During this particular phase of sleep, the muscles are typically completely relaxed whereas only the eyes are moving rapidly (hence the name for rapid eye movements- REM).

In case of patients affected by RBD, it may result in speaking, shouting and moving during sleep, sometimes also impacting the bed partner.

According to recent studies, it is estimated that around one percent of the population over the age of 60 is affected by RBD, occurring more frequently in men than women.

What causes RBD?

Up to now, the exact cause of RBD has not been discovered. However, the mechanism of the disease is being studied, and it is thought to be due to a disruption of the functional connections between the brainstem and regions of the brain that control emotions. This leads to changes in the control over muscle activity during the REM-phase of sleep. Importantly, RBD can be associated with other neurological disorders such as Parkinson’s disease.

RBD is very rare among adults below 40 years old, as the disease occurs typically after the age of 50. For the younger population, it may occur as a part of other neurological disease such as narcolepsy, specific autoimmune disease or due to the intake of medications such as antidepressants.

How do I know if I have RBD?

As people are not aware of their actions during RBD episodes, it is difficult to notice the disorder on your own. However, you might notice things when you wake up, such as objects in your surroundings that have been disturbed during the night. Hitting objects could also wake you up. More typically, your bed partner will report symptoms such as strong movement or speaking. It is usually possible to wake up during the episodes, where people are generally coherent, alert, they remember their dreams and can relate the body movements or gestures with their dreams.

For an RBD diagnosis, please consult a physician specialised in sleep (neurologist or pneumologist) who will evaluate the degree of probability and could eventually initiate diagnostic measures in a sleep laboratory where your body functions are monitored during the different phases of sleep.

Are there different stages of RBD?

Typically, symptoms of RBD gradually get worse, but sudden onset has also been reported. In the case of a gradual aggravation, affected people might first experience minor twitching of muscles or vocal expression, becoming more violent, with more complex gestures as time passes. Such episodes can occur once or multiple times per night, typically starting after 90 minutes of sleep which usually correspond with the beginning of the first REM-phase.

At what age can you develop RBD?

The onset of symptoms indicating RBD has been reported throughout all age groups. However, its occurrence within the population increases with age. People are most commonly diagnosed with RBD between 60 and 70 years old, after reporting symptoms for several years.

Thus, the Luxembourg RBD study focuses on participants over 55 years old to be able to better compare the results between the different participants and due to the low estimated RBD prevalence below this age.

What are the symptoms and implications of RBD?

The most typical manifestation of RBD is to act out dreams by movements such as kicking, punching or flailing along with vocal expressions such as talking, shouting or bursting out. When people wake up during such episodes, they can usually recall their dream. These symptoms increase the risk of injuries for the patient and his/her bed partner, especially if they become more severe over time.

Moreover, people with RBD have a higher risk of developing neurological diseases, such as Parkinson’s disease, in the future. RBD might thus be an indication for the onset of such conditions. To identify treatments for prevention or to develop compounds slowing the progression of neurodegenerative diseases, it is essential to understand the first signs and evolution of these diseases already in an early phase. The results of the Luxembourg RBD study will provide important knowledge for such research on better treatments for RBD-associated neurodegenerative disorders.

How can you treat RBD?

RBD can be treated with medication which can significantly reduce the symptoms and improve sleep quality. Multiple treatment options are available. Consulting a specialist and having a formal RBD diagnosis can set an individualised treatment plan based on your personal symptoms and medical history.

Moreover, some simple interventions can be carried out to reduce the risks of getting hurt during uncontrolled movements:

  • Moving objects away from the bedside;
  • Moving the bedside away from the window;
  • Place paddings or the mattress itself on the floor or install bed rails to avoid falling out of bed.

Can you inherit RBD?

There are recent studies on the genetic heredity of RBD. So far, the results indicate that first-degree relatives of RBD-affected persons are more likely to develop RBD themselves than a control group. This suggests a genetic component of the disease; however, its exact mechanism has not been discovered yet.

What are the risk factors? Can lifestyle, nutrition or medication impact RBD and its symptoms?

There are several risk factors known for RBD, which include a low level of physical activity, diabetes, head injuries, neurological disorders, smoking, excessive consumption of alcohol or medication such as antidepressants. The onset of RBD depends on the interplay of several factors. Generally, a healthy lifestyle can be considered beneficial and reduce the probability to develop RBD.

Notably, the environmental and behavioural risk factors for RBD are largely similar to those associated with Parkinson’s disease, which supports a link between RBD and Parkinson’s.

I do sleepwalk sometimes. Do I have RBD?

Sleepwalking is a different sleep disorder, characterised as a non-rapid eye movement (NREM) sleep disorder. Affected people might experience movements similar to RBD while sleepwalking – however, waking up from sleepwalking is usually harder than during an RBD episode. Also, after waking up from sleepwalking, people are usually less aware and hardly remember their dreams. More complex symptoms such as walking around while sleeping, eating, drinking or doing other everyday activities rather relate to sleepwalking and do not indicate RBD.

What is the relation between RBD and Parkinson’s disease?

RBD occurs due to brain dysfunction, which causes the muscles to be active instead of resting (as it is normally the case during the REM phase of sleep). Scientific studies observed that a significant percentage of people with RBD also develop a neurodegenerative disorder, such as Parkinson’s disease, at a later stage in life.

Thus, with the Luxembourg RBD study, researchers hope that by closely monitoring a group of participants affected by RBD, they will learn more about the early signs of Parkinson’s disease and its evolution. They aim to better understand the risk factors that play a role in the transition from RBD to the onset of Parkinson’s disease. This will be the basis to develop new strategies to treat or prevent Parkinson’s disease.

Do all people with RBD get Parkinson’s disease - and vice versa?

The diagnosis and onset of RBD do not necessarily mean the onset of Parkinson’s disease now or in the future. However, as both are based on neurological disorder and share many risk factors, the probability of developing Parkinson’s in the course of RBD is significantly increased.

In turn, not all patients with neurodegenerative diseases like Parkinson’s disease have RBD and no connection between RBD and Alzheimer’s disease was found so far.

Taken together, this causes a high prevalence of RBD among patients with Parkinson’s disease which is estimated to be 33 – 50 % and even higher in more rare forms of parkinsonism like Dementia with Lewy bodies and Multiple System Atrophy.

Can treatment of RBD alleviate the progression to Parkinson’s disease?

At the moment, there is no medication available that can interfere with an underlying neurodegenerative process that may cause a transition from RBD to Parkinson’s disease.

Which medication can reinforce the symptoms of RBD?

Commonly, antidepressants like serotonin reuptake inhibitors might trigger or exacerbate the symptoms of RBD. To investigate if one of your current medications might also induce the onset of RBD, please consult your treating physician.

What is the aim of the study?

Researchers aim to know how many people in Luxembourg have RBD and to investigate the link between RBD and Parkinson’s disease in more details. The strategy is to closely monitor a group of participants affected by RBD, thereby learning more about the early signs and risk factors of the disease and its evolution. Ultimately, this may improve diagnosis at an earlier stage allowing for an earlier and thus more efficient treatment.

Why should I participate?

The link between Parkinson’s disease and RBD is not yet known in sufficient detail. To determine the incidence of RBD in the Luxembourgish population and increase the chances of having a sizable group with RBD, a large group of volunteers needs to answer to the survey is needed to achieve the study’s goals.

With your participation, you will not only actively support biomedical research, but ultimately also contribute to the development of novel strategies for the diagnosis and treatment of Parkinson’s disease.

Is the participation remunerated?

No. Generally, participation in a research study does not foresee any remuneration or financial compensation.

There are also no costs or charges associated with your participation at any stage of the study. All medical examinations and diagnostic procedures are offered cost-free.

Does the participation require changes in my medical treatment?

No. The Luxembourg RBD study is observational and you will not be given any medication nor asked to change your treatment.

How much time does it take to participate? What do I have to do?

If you agree to participate in the study, you will participate in an online questionnaire by logging in with a token in the letter you receive by mail. The questionnaire takes approximately 10 minutes to fill and will assess your sleep behaviour and potential symptoms.

In a second step, the study team will contact participants more likely to have RBD by phone for a short interview. These participants will then receive an easy-at-home smell test along with a second questionnaire by mail. At this stage, the fact that you are re-contacted does not mean that you are diagnosed with RBD.

Then, participants with the highest probability of having RBD will be offered additional questionnaires and tests and invited to the Parkinson’s Research Clinic for neurological and neuropsychological examinations.

Finally, participants showing no signs of neurodegenerative diseases and suspected to have RBD will undergo a sleep assessment in a sleep laboratory in a hospital by an at-home sleep assessment device. If the RBD diagnosis is confirmed, participants will be invited to join the longitudinal study, which means yearly follow-up visits and sampling of biological fluids (blood, urine and saliva) along with neurological and neuropsychological assessments.

Do I get a personal medical assessment?

Participants who have completed the first steps of the study, i.e., both questionnaires and smell test (see above), and were selected for further follow-up, will receive an invitation for a personal assessment at the Parkinson’s Research Clinic. During this medical assessment, you will undergo neurological and neuropsychological examinations before defining if you qualify for the last step of the study. In the final step, participants will undergo sleep analysis to confirm the diagnosis of RBD.

If your responses do not suggest a possible RBD, you will not be recontacted and you won’t be invited to a personal assessment as the probability of having RBD is very low. In case of doubt regarding your sleep quality, we advise you to consult your treating physician for further medical follow-up.

What happens to my personal data and the samples taken during the course of the study?

Personal data and biological samples are collected and analysed to meet the goal of the study. Biological samples are safely stored at the Integrated BioBank of Luxembourg (IBBL). The personal data are stored at the encrypted data servers located at the Luxembourg Centre for Systems Biomedicine (LCSB, University of Luxembourg), which implements appropriate security measures.

All data are pseudonymised, meaning that a confidential reference code will be used instead of your personal identifiable information. This code alone does not allow you to be directly identified and will only be used for the scientific processing of your data. Only authorised members of the research team can access them. Participants can withdraw the consent of storing the personal data at any time without giving a reason by contacting our team. Such a decision will not affect the participants in any way. They can also ask for their data to be removed from the database.

Will the information I provide be shared with my treating physician?

By default, no data will be shared with treating physicians. However, the study team can share your study results with your treating physician if you wish. It may contribute to choosing the best medical treatment if you experience sleeping problems. For people affected by unexplained sleep disorders, participation in the study may help diagnose RBD, initiate treatment to improve sleep quality and plan further follow-up with their treating physician.

What happens if my online survey results indicate that I might have RBD?

Your online survey answers will be analysed and, in case there is a higher probability for RBD diagnosis, you will be re-contacted by phone by our team. This phone call aims to reconfirm the information related to the answers in the online survey. At this stage, the fact that you are re-contacted does not mean that you are diagnosed with RBD.

After the phone interview, you may receive by mail an easy-at-home smell test with a second questionnaire. Then, participants with the highest probability of having RBD will be contacted by phone and invited to the Parkinson’s Research Clinic for a complex neurological and neuropsychological examination.

In case you are not affected by any neurological impairment, you will be invited to undergo a sleep assessment at a sleep laboratory in a hospital and/or use an at-home sleep assessment kit.

What happens if I am diagnosed with RBD?

In case the sleep assessment confirms the RBD diagnosis, a team member will inform you and discuss the further steps of the study for which you qualify: an annual assessment by the team neurologist, neuropsychologist and research nurse, with additional optional visits in-between. Additionally, you will be referred to your treating physician for medical follow-up in parallel with the study, possibly involving a neurologist/sleep specialist.

What happens during the examinations and at the sleep lab?

Participants with the highest probability of having RBD and no signs of neurodegenerative disease undergo a sleep assessment by either polysomnography in a sleep laboratory in a hospital or an equivalent modality (mobile sleep assessment device – see below). Polysomnography involves the simultaneous recording of electroencephalogram (brain activity), electrooculogram (eye activity), and electromyogram (muscular activity) signals during one night of sleep. This procedure is non-invasive and does not pose any specific risk to the participant.

Additionally, a novel at-home sleep assessment will be used during at least two consecutive nights in a subset of participants. The chosen participants for the at-home sleep assessment will be instructed by the Parkinson’s Research Clinic professional team.

If you qualify for an appointment in the sleep lab, you are asked to spend two consecutive nights there to monitor your sleep behaviour. This means that you will undergo a non-invasive and standard assessment of sleep disorders called polysomnography. At the sleep lab, you are videotaped while sleeping to register your movements and your brain activity is measured (by electroencephalogram) during sleep. You are informed about the detailed procedure on-site and asked for your consent.

What is an at-home sleep assessment mobile device?

This device is a new alternative to the standard polysomnography. The participant may be asked to visit the sleep laboratory and/or receive a sleep assessment mobile device to use at home. In this case, the participant receives in-person step-by-step instructions along with the device to take home. As in the sleep lab, the device will capture motion and includes a camera and tripod to record movement during sleep. The assessment should be done over 2 consecutive nights.

What if I change my mind and don’t want to participate anymore?

If you decide to withdraw your participation in the study, you can do so at any time, without giving a reason and without any further consequences or disadvantages for you.

How could I benefit from my participation?

Participants should not expect an immediate benefit from the study, as the main reason to participate is to help researchers better understand and find better treatments for RBD and associated neurodegenerative disorders. However, for participants with yet unexplained sleep behaviour disorders, the study’s procedure may help diagnose RBD. Once a diagnosis is confirmed, an efficient treatment can be initiated to improve sleep quality in parallel with the study. Some participants could also benefit from the diagnostic procedures looking for any signs of parkinsonism and cognitive impairment. If an underlying neurodegenerative disorder is identified, the participant will be referred to his treating physician/specialist for further diagnostic and treatment measures.

The regular follow-up visits offered to participants with RBD may be beneficial for them by helping monitor their health status and recognise potential new symptoms. Participants with RBD that develop further into a neurodegenerative disease may profit from early access to existing treatments and future trials to prevent or slow down the neurodegenerative process.

Please note that we cannot provide a personal medical assessment to every participant, but only to the ones where RBD is highly probable based on the results of the questionnaires and tests.


In either case, your participation – even if you sleep well – is highly valued and will help us know how many people in Luxembourg suffer from RBD. All participants indirectly contribute to the development of new diagnostic tools and future neuroprotective treatments.

Why is the survey not available in Luxembourgish?

For medical or psychological questionnaires to be used in research in a specific language, it is very important that they are standardised and validated. This is necessary to reach the highest standard of research quality and make answers comparable in the international research community. Such research surveys are generally established in languages that are spoken in different countries in the world. For Luxembourgish such standardised questionnaires unfortunately often do not exist. Therefore, we have provided standardised versions of the questionnaires in other 4 most used languages of the country: French, German, English and Portuguese. We thank you for your understanding!

Can I also take part in the online survey in person or by phone?

You can only fill the questions online. If you require assistance in filling out the survey form, you can call the RBD study team (+352 44 11 48 48) who will gladly assist and guide you through the process.

I don’t live in Luxembourg. Can I participate?

The study can only include Luxembourg residents between the age of 55 and 75.

I think I have RBD, but I am outside the target group (under 55, over 75). Can I still participate?

Unfortunately, no. The study does not include people younger than 55 or older than 75 years due to the low prevalence of RBD or confounding factors in these age groups, respectively.

I am younger than 55 or older than 75, but one of my family members has/had RBD or Parkinson’s disease? Can I participate?

As indicated above, the Luxembourg RBD study is designed for an age group between 55 and 75 years only. If you suspect you have RBD based on observed symptoms or reports by your bed partner, please consult your treating physician.

I have been diagnosed with RBD or Parkinson’s disease and I am in the target audience (55-75 years old). Can I still participate in the survey?

Yes, you can participate even if you have already been diagnosed with RBD or Parkinson’s disease, and you’re between 55 and 75 years old. The aim of the survey is to determine the incidence of RBD in Luxembourgish population.

Can I stop the survey and continue it later?

You can access the online questionnaire with the personal token you receive in the letter. Once the survey was started, it must be filled in one go. It is not possible to pause the survey and get back to it on a later stage.

Until when can I answer the survey?

The deadline for filling in the survey will be 2 months after the letters with the token were sent to you.

I am between 55 and 75 but did not receive/lost my letter. What should I do?

If you are within the target group of the study but do not have the letter anymore, you can call the RBD study team (see phone number below). They will assist you.

In which languages can I answer the survey?

The online survey is available in French, German, Portuguese and English. Similarly, at all other stages of the study, communication in all of the above languages will be possible. Our study team speaks all four languages above as well as Luxembourgish.

Is it safe to visit the clinic/sleep laboratory during the current COVID-19 pandemic?

We are fully aware that the current pandemic situation imposes many challenges. We are taking all the necessary and required sanitary measurements to minimise the risk of infection. The visits will be possible while respecting the actual public regulations. Should you have questions, after receiving the invitation, please address them to the Luxembourg RBD study team to discuss your situation.


Whom can I contact in case of issues with the survey or any further questions on the study?

In case of further question, you can call the helpline of the Luxembourg RBD study team (+352 44 11 48 48, Mon. – Fri. 08:00 - 16:30h) or send an email (rbd@uni.lu).

Any other questions, please contact the Parkinson’s Research Clinic: +352 44 11 4848


The project is organised by the University of Luxembourg (UL), the Luxembourg Institute of Health (LIH), the Integrated Biobank of Luxembourg (IBBL), the Centre Hospitalier de Luxembourg (CHL) and the Laboratoire National de Santé (LNS) under the framework of the National Centre of Excellence in Research on Parkinson’s Disease (NCER-PD). The project is financed by the Luxembourg National Research Fund (FNR). This survey is under the patronage of the Ministry of Health.