A Little-Understood Sleep Disorder Affects Millions and Has Clear Links to Dementia

4 questions answered

Past age 50, men are much more likely to have REM sleep behavior disorder than women. Ground Picture/Shutterstock

A little-known and poorly understood sleep disorder that occurs during the rapid eye movement, or REM, stage of sleep has garnered attention for its role in foreshadowing neurodegenerative brain diseases such as Parkinson’s disease and Lewy body dementia. The disorder, known as REM sleep behavior disorder, or RBD in the medical field, affects around 1 percent of the general population worldwide and about 2 percent of adults over 65.

The Conversation talked with Dr. Anelyssa D'Abreu, a neurologist specializing in geriatric neurology, to discover what researchers know about the condition’s links to dementia.

1. What Is REM Sleep Behavior Disorder?

Every night, you go through four to five sleep cycles. Each cycle, lasting about 90 to 110 minutes, has four stages. That fourth stage is REM sleep.