02/12/2012 10:58 am ET

Valentine's Day: How Love Changes Your Body Chemistry

By Danny Deza

Ah, love. In the heady days of a mutual crush, pulses race, knees go weak and heads reel. So strong are these feelings, they've launched a thousand songs and poems.

But it's more than just a metaphor. Love does indeed impact our bodies in measurable ways.

You feel different and are different. Read on to find out what researchers have discovered about this thing called love.