When a new study published in JAMA Network Open reported that men who sleepwalk are nearly five times more likely to develop Parkinson's disease, most news coverage understandably led with the alarming numbers. Men with probable REM sleep behavior disorder faced 6.4 times the risk. Those with both conditions had 8.4 times the odds.
But neurologists who specialize in this area say the headline risk statistics, while real, miss the more clinically important part of the story — one that could eventually change how Parkinson's disease is detected and even prevented.
Two Different Sleep Disorders, Two Different Threat Levels
The study, which analyzed data from 25,694 men in the Health Professionals Follow-Up Study, examined two types of nighttime behavior that are often lumped together but are neurologically distinct.
Sleepwalking occurs during deep, non-REM sleep. The sleeper performs complex behaviors — walking, talking, sometimes leaving the house — while largely unconscious. It's common in children, tends to run in families, and in most cases is not linked to serious neurological disease.
REM sleep behavior disorder (RBD) is different in almost every respect. It occurs during REM sleep — the stage when most dreaming happens — and involves people physically acting out their dreams. Someone with RBD might shout, punch, kick, or leap out of bed while asleep, often with no memory of the episode. Their bed partner is typically the one with the bruises.
The distinction matters because RBD carries a far more ominous neurological implication than sleepwalking. During normal REM sleep, the brain sends signals to temporarily paralyze the muscles — a mechanism that keeps people from acting out their dreams. In people with RBD, that paralysis mechanism fails. And in many cases, the failure is an early sign that something is going wrong in the same regions of the brainstem that Parkinson's disease later destroys.
The Prodromal Window
Parkinson's disease is typically diagnosed based on its most visible symptoms: tremor, rigidity, slowed movement. But by the time those motor symptoms appear, studies suggest that roughly half of the dopamine-producing neurons in a key brain region called the substantia nigra have already been lost.
This is why neurologists have been so interested in what they call the "prodromal" phase of Parkinson's — the period before motor symptoms appear, sometimes lasting a decade or more, when the disease process is already underway but hasn't yet reached the movement control centers of the brain.
RBD has emerged as one of the most powerful prodromal markers known. Long-term follow-up studies have found that approximately 73% of people with RBD will develop a neurodegenerative disease — Parkinson's, Lewy body dementia, or multiple system atrophy — within 10 years of diagnosis. At 14 years, that figure climbs to around 92%.
The implication is significant: a diagnosis of RBD doesn't mean Parkinson's is inevitable or imminent. It means a person may be standing at the beginning of a long runway — one that researchers are now racing to understand, and potentially to shorten the odds of the landing being bad.
A Decade to Intervene
The emerging field of prodromal Parkinson's research is built on this premise. If RBD reliably predicts neurodegeneration years before it becomes symptomatic, then people with RBD could become the ideal candidates for neuroprotective therapies — drugs or interventions designed to slow or halt the underlying disease process.
Several clinical trials are currently enrolling or in development specifically targeting people with RBD before Parkinson's symptoms appear. The logic is straightforward: if you wait until someone has motor symptoms to start treatment, much of the damage is already done. But if you could intervene while the dopamine system is still largely intact, the potential to preserve function is far greater.
"These individuals represent a golden opportunity for prevention trials," researchers have noted in recent literature. Unlike the general population, where Parkinson's affects roughly 1 in 100 people over 60, people with diagnosed RBD have conversion rates high enough to make clinical trials feasible within practical timeframes.
This reframes the JAMA Network Open findings considerably. The elevated Parkinson's risk among men with sleepwalking and RBD isn't only cause for alarm — it's also a signal that identifies people who might benefit from earlier monitoring, and eventually, earlier intervention.
Why Men? And What About Women?
The study's focus on men reflects both the demographics of its source cohort — the Health Professionals Follow-Up Study, which enrolled male health workers — and a broader gap in Parkinson's research that scientists have increasingly flagged.
Parkinson's disease affects men at roughly twice the rate of women, but the reasons for this disparity are not fully understood. Some researchers have proposed hormonal explanations, while others point to differences in environmental exposures. What's less clear is whether women with RBD face the same conversion rates to Parkinson's as men do, or whether sex-based differences in the disease's prodromal phase mean the findings from male cohorts may not translate directly.
Large-scale studies of women with parasomnias and neurodegenerative disease risk are underway, but they lag significantly behind the male-focused research. For now, clinicians treating women with suspected RBD are generally applying the same monitoring and counseling frameworks developed from male data — an acknowledged limitation that researchers say needs to be addressed urgently.
How to Tell Sleepwalking From RBD
One challenge in applying these findings is that most people don't know which type of parasomnia they have — and sleepwalking and RBD can look similar from the outside.
Several features can help distinguish them, though formal diagnosis requires a sleep study:
Signs more consistent with RBD:
- Episodes occur in the second half of the night, when REM sleep is most concentrated
- The person appears to be responding to a dream (defending themselves, reaching for something, reacting emotionally)
- If awakened, they can often recall a dream that matches the behavior
- Onset is typically in middle age or later; new-onset "sleepwalking" in someone over 50 is a red flag
- The person may have other early Parkinson's indicators: reduced sense of smell, constipation, acting out dreams before full episodes begin
Signs more consistent with non-REM sleepwalking:
- Episodes occur in the first third of the night, during deep sleep
- Behavior is more automatic than reactive (walking, performing routines)
- The person is difficult to rouse and confused if awakened
- No dream recall
- History going back to childhood
Anyone experiencing new-onset sleep behaviors in middle age or older — particularly behaviors that seem to reflect dream content — should discuss the symptoms with a physician. A formal sleep study (polysomnography) can confirm or rule out RBD by recording both brain activity and muscle tone during sleep.
The Limits of the Study
It's worth noting what this research can and cannot show. The JAMA study relied on self-reported questionnaires rather than objective sleep studies, meaning some participants classified as having probable sleepwalking or RBD may have been misclassified in either direction. The cross-sectional design also means the data reflects a snapshot in time rather than following individuals forward to track who actually developed Parkinson's.
The authors, along with researchers at the Parkinson's Foundation, have emphasized that these are population-level associations — most people with sleepwalking never develop Parkinson's, and the same is true even for many people with RBD. Elevated risk is not a diagnosis, and panic is not a useful response to a sleep disorder.
What is useful is awareness: knowing the difference between benign childhood sleepwalking and a new sleep behavior that warrants medical attention, understanding that RBD is not just a curiosity but a potential neurological signal, and knowing that if a diagnosis of RBD is confirmed, the field of preventive neurology is moving quickly toward options that didn't exist a decade ago.
What to Do Now
For most people who occasionally sleepwalk or have episodes dating back to childhood, the risk picture from this study is not particularly concerning. Non-REM parasomnias in younger adults, while disruptive, are not the same neurological warning sign as RBD.
For those with symptoms that might suggest RBD — especially anyone over 50 with new sleep behaviors, a bed partner who reports being kicked or hit during the night, or episodes with apparent dream content — the recommended steps are:
- Document the episodes. Date, time of night, behavior observed, any associated dream recall. Video if possible and safe.
- Talk to a primary care physician. Mention the concern about RBD specifically — it may not come up otherwise.
- Request a sleep study referral. Standard overnight polysomnography with video monitoring can confirm or rule out RBD.
- Ask about prodromal Parkinson's monitoring. Some academic medical centers now offer structured follow-up programs for people with confirmed RBD that include smell testing, dopamine imaging, and enrollment in prevention trials.
- Treat associated conditions. Poor sleep, untreated sleep apnea, and certain medications (including SSRIs and some blood pressure drugs) can worsen or mimic RBD and should be addressed regardless.
The science connecting RBD to neurodegeneration is no longer preliminary. What's changing is the willingness to use that connection proactively — not just as a warning, but as a starting point for the kind of early intervention that Parkinson's disease has never before had access to.
