Anything that activates the joy center in the brain makes you happy, and therefore protects you. Oddly enough, that's what they do in 'Harry Potter': The nurse gives the kids chocolates when they've been near the Dementors!

Quote

“Anything that activates the joy center in the brain makes you happy, and therefore protects you. Oddly enough, that's what they do in 'Harry Potter': The nurse gives the kids chocolates when they've been near the Dementors!”