REM behaviour disorder

Rapid eye movement behavior disorder or REM sleep behavior disorder (RBD) is a sleep disorder in which sleep paralysis, which normally disables the voluntary muscles during REM sleep, fails to occur. The result is that the sufferer acts out movements that occur in dreams, especially during dramatic episodes, sometimes with injurious results.

REM behavior disorder is relatively uncommon. No causes are yet known for it, though about half of cases have been associated with neuropathies, and it may be a warning sign for Parkinson's disease. The majority of sufferers are male.