Relying on caffeinated beverages to get you through those long nights (as well as the long, last minute detail-filled days) just adds fuel to the bad-for-you fire. "Caffeine is a stimulant and an irritant, especially to the nervous system," says Lipman. "You're going to have a lot of anxiety and nerves to begin with. You don't need to add to your stress." And caffeine may even wreak havoc on your bridal beauty. "Caffeine is very dehydrating and can contribute to dark circles under your eyes," says Jaliman. What's more, caffeinated beverages—whether they're energy drinks or frothy Starbucks mainstays—pack a ton of extra sugar. Experts agree you're OK to stick with your normal caffeine consumption, but don't overdo it!