Booze blows because it feels oh-so-good — until you wake up wishing you were dead. Alcohol upsets the levels of neurotransmitters like serotonin (which explains why you love everyone, man) and the brain's reward chemical, dopamine (leading you to believe that downing another Long Island is the awesomest idea).
But the hooch has you hoodwinked: Elsewhere in your body, it's on a warpath straight to your hangover. Alcohol breaks down into an even worse toxin (hence the nausea and vomiting), dilates blood vessels in the brain (the throbbing headache), and blocks the antidiuretic hormone vasopressin, tricking you into peeing out too much water (the severe dehydration). Besides fatigue, you can blame Sunday's fog on a hungry noggin: Your liver is so slammed, it's not sending enough glucose to your brain.
How to avoid this biological havoc? Have another drink and get that tolerance up! (You might also want to put your name on the liver transplant registry.) Or there's always the boring approach: moderation.
