Everything we know about hangovers - and how to make the pain go away

A night of Guinness and Irish whiskey? Fun. The next morning? Not so fun - and to make matters worse, a workday.

Newton's third law states that for every action there is an equal and opposite reaction.

And while he was talking about physics, not biology, it certainly feels like hangovers follow that law, though we might rephrase it as "for every moment of inebriated exhilaration, there is an equal and opposite feeling of pain and unease."

But what is it about throwing back a few too many that leaves you feeling only halfway human: your head throbbing, your mouth dry, your stomach on edge? Could that feeling really be explained by dehydration, as so many seem to think?

In short, the answer is no - hangovers are more complicated than that. And in fact, much about hangovers is still a mystery to scientists. But here's what we know.

And just a note: We're looking at hangover symptoms specifically here, not the effects of long term alcohol abuse. Frequent hangovers could be a sign that you should consider cutting back on drinking.