That would explain a thing or two.

Cigarettes and alcohol go together like peanut butter and jelly. Oh, what a tasty pairing. I'm pretty sure that, in combination, they form a complete protein or something. However, here's a troubling interaction I didn't expect.

To mimic more closely the effect in human drinkers, Chen and his colleagues studied the effects of binge drinking in adult rats. They injected rats' stomachs with a dose of alcohol roughly equivalent to around four or five drinks in quick succession; enough to make their blood alcohol hit double the United States legal driving limit of 0.08%. The team also gave the animals a range of nicotine doses similar to those in the bodies of light, moderate or heavy smokers.

In 'heavy smoking' animals, the nicotine slashed the rats' peak blood-alcohol level, which came about an hour after injection, in half. Blood alcohol of 'moderate smoking' animals dropped by around 30%, and animals mimicking light smokers were not affected. The results are reported in the journal Alcoholism: Clinical & Experimental Research.

Good news, right? Well, not exactly. That smokers drink more is a widely observed phenomenon. If the same nicotine-alcohol reaction takes place in humans, what it likely means is that smokers are simply drinking more to get the same sensation. And then there's the big catch: cutting the BAC in this fashion doesn't do anything to reduce the additional hangover potential those extra drinks bring.