Fun science fact: an actual hangover, the kind you get after a weekend-long binge at the Beer, Bourbon, Bacon and Baked Beans festival, is caused by a wide variety of factors.
Dehydration is the most well-known cause, but there's also irritation of the stomach lining, a decrease in blood sugar, immune system reactions, the mysterious effects of congeners (like the tannin in wine) and the simple fact that you stayed up late, slept poorly and ingested lots of hard-to-digest goodies.
A Super Bowl hangover, like the real thing, is also caused by a wide variety of complex factors.