Vitamin/Mineral depletion. Drinking alcohol depletes necessary vitamins and minerals from the body. Especially Magnesium which would result in the shaking, body or hand tremors, even the charlie horses we get in the night. Potassium is also depleted pretty badly. Try taking a Cal/Mag/Potassium supplement a couple of hours before drinking to help keep your levels even for the night.
Dehydration!! Alcohol is well known for this, and muscles ache because of it as well. Try to drink something soft(like fruit juice) inbetween and you won't suffer as much the next day!
http://www.minddisorders.com/A-Br/Alcohol-and-related-disorders.html
Read the 12th paragraph. The whole article is excellent.