REM sleep behavior disorder, often called RBD, is one of the most common symptoms in Lewy body dementia. More than 75% of people with Lewy body dementia experience it at some point, and for many people, it shows up years before any cognitive or movement problems begin.

In RBD, people physically act out their dreams. They might punch, kick, yell, or thrash around while completely unconscious. The episodes can be violent enough to cause injuries. If your loved one has been doing this at night, it’s not something to dismiss as just restless nights or bad dreams. It’s a significant symptom that connects directly to what’s happening in their brain.

This article explains what REM sleep behavior disorder is, why it happens in Lewy body dementia, and how to manage it safely.

What Is REM Sleep Behavior Disorder?

During normal sleep, your body cycles through different stages. One of these stages is called REM sleep, which stands for rapid eye movement. This is when most vivid dreaming happens. Normally, your brain temporarily paralyzes your muscles during REM sleep. This natural paralysis keeps you from acting out whatever you’re dreaming about.

In RBD, that protective paralysis doesn’t work properly. The person’s body remains able to move while they dream, so they act out what’s happening in their dreams.

The episodes typically happen in the second half of the night, when REM periods are longer and dreaming is most intense. You might notice your loved one punching or kicking the air, thrashing around, yelling, or making running motions with their legs. Sometimes they sit up suddenly or swing their arms.

What they’re doing matches whatever is happening in their dream. If they’re dreaming about being attacked, they’re fighting back. If they’re dreaming about running from something, their legs move like they’re running. The movements aren’t random.

During these episodes, they’re completely asleep. Their eyes stay closed. If you try to wake them, they usually don’t respond, though sometimes they wake themselves up if they move violently enough or fall out of bed. When they do wake up, they’re often confused and disoriented.

Most people have no memory of what happened. In the morning, they might remember having vivid or violent dreams, but they don’t know they were actually moving or making noise. You might be the one who has to tell them about bruises they don’t remember getting or explain why you moved to another room during the night.

The episodes don’t follow a predictable schedule. Your loved one might have them multiple times a week for a while, then go months without any episodes.

Why It Happens in Lewy Body Dementia

As we mentioned earlier, during REM sleep, your brain automatically shuts down most of your muscles. You can still breathe and move your eyes, but everything else is temporarily paralyzed. This protective mechanism keeps you from acting out your dreams. The part of the brain responsible for this is called the brainstem.

In Lewy body dementia, Lewy bodies accumulate in these brainstem areas, causing the automatic paralysis to fail. Without that protection, your body can move freely while you’re dreaming.

This brainstem damage happens early in Lewy body dementia, often years before Lewy bodies spread to other parts of the brain that control thinking, memory, or movement. That’s why RBD can show up a decade or more before any cognitive problems appear. 

The same brainstem areas affected in RBD also control other automatic body functions. If your loved one has blood pressure problems when standing up, chronic constipation, or trouble regulating body temperature, along with the sleep issues, that’s probably not a coincidence.

REM sleep behavior disorder is one of the strongest early indicators of Lewy body dementia. Research shows that many people with RBD eventually develop either Lewy body dementia or Parkinson’s disease, often years after the sleep symptoms first appear.

If your loved one has RBD by itself with no other symptoms, doctors may just monitor the situation. But if the sleep problem occurs alongside visual hallucinations, confusion that comes and goes, or movement problems similar to Parkinson’s disease, Lewy body dementia becomes very likely.

This is why you need to tell doctors about any history of acting out dreams, even if it started years ago. That long history of RBD is crucial diagnostic information that helps doctors distinguish Lewy body dementia from other conditions.

Making the Bedroom Safer

Safety is the top priority when managing RBD. Because people can injure themselves or their bed partners during episodes, making the sleep environment safer is really important.

Here are some practical steps that can help:

Remove or secure objects that could cause injury. Lamps, clocks, glasses, and other items on nightstands can become projectiles or breakable hazards. Keep them in drawers or on surfaces farther from the bed. If there are guns or other weapons in the bedroom, remove them completely.

Lower the bed or place pillows or the mattress directly on the floor. Many injuries happen when people fall out of bed during an episode. A lower surface means less distance to fall and less force on impact.

Pad sharp corners on furniture near the bed. Nightstands, dressers, and bed frames with sharp edges can cause cuts or bruises during episodes. If furniture can’t be moved, add padding to corners and hard edges.

Clear a safe path to the bathroom. If your loved one gets up during the night, make sure they won’t trip over shoes, clothing, or other items in the dark.

Secure windows. Make sure windows are locked or have barriers to prevent falls, especially if the bedroom is not on the ground floor.

Consider sleeping arrangements. If episodes are frequent or violent, sleeping in separate beds or separate rooms temporarily may be the safest option for everyone involved.

Treatment Options

The good news is that RBD often responds well to treatment. The two medications most commonly used are melatonin and clonazepam.

Melatonin is usually the first choice for people with Lewy body dementia. It’s a hormone naturally produced by the body to regulate sleep, and taking it as a supplement can help reduce RBD episodes. Doses typically range from 3 to 12 mg taken at bedtime. Melatonin has fewer side effects than other options and is generally considered safer for older adults and people with dementia. Some people experience morning grogginess or headaches, but these are usually mild.

Clonazepam is a benzodiazepine medication that has been used for RBD for many years. It can be effective, but it needs to be used carefully in people with dementia because it can worsen cognitive problems, increase the risk of falls, and cause daytime drowsiness. It may also worsen sleep apnea if that’s also present. For these reasons, doctors often prefer to try melatonin first in people with Lewy body dementia.

Your loved one’s doctor will consider their overall health, other medications, and specific symptoms when recommending treatment. Sometimes a combination approach works best.

It’s worth noting that even with medication, safety measures should stay in place. Treatment reduces episodes but may not eliminate them entirely.

What to Tell Your Doctor

If you think your loved one has RBD, describe what you’re actually seeing. Don’t just say “restless sleep” or “bad dreams.” Be specific about the movements, sounds, timing, and frequency.

Keep notes about episodes for a few weeks before the doctor’s appointment. Write down when they happen, what time of night, what kinds of movements you observe, whether the person wakes up, and what they remember, if anything. Note any injuries that occur.

Mention how long this has been happening. If your spouse has been acting out dreams for ten years and cognitive problems just started recently, that timeline is diagnostically important. Doctors need to know RBD came first.

Ask whether a sleep study would be helpful. Not everyone with RBD needs a formal sleep study, but it can confirm the diagnosis and rule out other sleep disorders. The decision depends on how clear the symptoms are and what other conditions doctors are considering.

If your loved one is already diagnosed with Lewy body dementia, make sure doctors know about the REM sleep behavior disorder. Even if it’s in the medical chart somewhere, explicitly bring it up when discussing treatment options. It affects which medications are safe to use and which should be avoided.

Living With RBD

For caregivers, RBD can be one of the more exhausting aspects of Lewy body dementia. Your own sleep gets disrupted. You may feel anxious about what might happen each night. Some caregivers describe feeling like they need to stay alert even while sleeping.

A few things that may help:

Talk to your loved one’s doctor about optimizing treatment. If current medications aren’t controlling episodes well, there may be room to adjust doses or try different approaches.

Make sure your own sleep needs are being addressed. If separate sleeping arrangements would help you get better rest, that’s a legitimate option to consider.

Connect with other caregivers who understand. Support groups for Lewy body dementia caregivers, whether in person or online, can provide practical tips and emotional support from people who’ve been through similar experiences.

Remember that your loved one isn’t choosing to do this and has no memory of their actions. They may feel embarrassed or upset when they learn what happened during the night. Reassuring them that you understand, that this is part of the disease and not something they can control, goes a long way.

If you need someone to talk to or have questions about managing RBD, our team is here to help. You can reach us every day of the year from 8am to 8pm Eastern time at 516-218-2026 or at 833-LBDLINE. You can also email us at norma@lbdny.org.