Lashing out in sleep is a sign of 'rapid eye movement behaviour disorder ' Half of people with this condition will go on to develop Parkinson 's disease . Up to 90 % of people will develop another neurological disorder within a decade . Sleep disorder occurs due to a brain malfunction - meaning the brain does n't paralyse the body 's muscles during the period of sleep when people dream .
Lashing out in sleep is a sign of 'rapid eye movement behaviour disorder ' Half of people with this condition will go on to develop Parkinson 's disease . Up to 90 % of people will develop another neurological disorder within 10 years . Sleep disorder occurs due to a brain malfunction - meaning the brain does n't paralyse the body 's muscles during the period of sleep when people dream .