What causes a muscle twitch?

Muscle spasm or twitch in muscle, what causes it? Is it something I need to be concerned about?

• It's been doing it for a little over four hours.

• Answer:

  One here and there is nothing to worry about. Usually they are caused by medications, not taking in enough fluids, not enough rest, too much exercise, or poor nutrition due to a diet. The problem usually resolves in a day or two. If it continues or becomes rampant, you should see a doctor to get checked out for less benign causes. Rehydrate. Eat a baked potato (skin and all) or peel a banana and eat it. Get some rest. It'll probably be gone by morning.