Down Syndrome

Those born with Down syndrome have an extra copy of a chromosome – chromosome 21 to be exact. As a result, the person develops differently than others, and it limits their cognitive development. While the syndrome is relatively common in the U.S., the exact reason babies are born with an extra chromosome is not known. […]

During normal REM sleep the body's muscles goes into a temporary paralysis while the brain is dreaming, but for people with REM sleep behavior disorder, paralysis doesn't occur. Instead their body and voice will act out their dreams while they remain asleep.