How your body reacts when you fall in love

Butterflies in your stomach, a racing heartbeat--you probably remember those symptoms well from your first middle school crush. As an adult, they're actually your body's subtle clues that you're falling in love (or lust, at least). At the start of a relationship, a series of truly fascinating chemical reactions occur throughout your nervous system and hormones. From the first time you meet to climbing under the sheets, here's what's happening to your body as you fall in love.