Ringing in the New Year with a champagne toast is a ritual as old as time itself. Its fizzy effervescence certainly makes for an appropriately celebratory drink. But too much of a good thing sometimes leads to becoming a bit more tipsy than we’d planned… and possibly a nasty hangover to boot. Of course, the main culprit is alcohol, but research suggests that the carbon dioxide in champagne may intensify its intoxicating effects.