Hand tremors, twitching while falling asleep and twitching during the day?!

For the past 6th months or so, I've noticed that my left hand has these "tremors" where my fingers and thumb will "curl in" randomly, so to speak. I've also noticed that while I'm falling asleep, I violently twitch. (and, according to my friends, I twitch violently while I'm asleep as well.) And finally, during the daytime, I'll twitch violently as well. This doesn't happen everyday, but it does happen quite often. I know it can't be tourettes syndrome, but could it be a neurological disorder?

(Also, it's never painful. But rather random)