Plagued by the ‘hypnic jerk’? 4 surprising causes of condition that could be early sign of Parkinson’s or heart attack

MANY are jolted awake by a twitch as they're drifting off to sleep, but what causes these sudden movements? Sleep experts say that involuntary twitches - known as a hypnic jerk - could be an early sign of Parkinson's disease or a heart attack, and they have now highlighted several surprising causes of the movements....