What Causes Shaking And Twitching After Consumption Of Alcohol?

i went out for drinks last night but i didnt have too much really. i went home early as i felt quite tired and nauseous. i fell asleep for like an hour but then i woke up and i was shaking and twitching hard and feel all disorientated. ive been drinking water and its settled down abit but its still there and its hard for me to get back to sleep. why is this happening as i didnt think i had drank that much?! :s