I grew up with a guy who was (fairly) normal. Our paths crossed after not seeing him in about 6 years and although he's still a good lad he's absolutely fucked with this head shake twitch thing. He tans about 4 cans of Asda's own brand red bull a day and openly admits has to swallow a load of sleeping pills to bring himself back down at night.
I asked him about the twitch one day and he said he doesn't even notice he's doing it now.
(not heart related, but still!)
Edit : to clarify, I was determined he'd took a bad E or something but he says he's never touched anything like that - and can't smoke weed to bring him down.