Will Chocolate Help Your Sleep or Destroy It?

Chocolate contains not only calories, but caffeine, especially dark chocolate.

A 1.55-ounce Hershey’s milk chocolate bar, for instance, contains about 12 milligrams of caffeine, or the same amount as three cups of decaffeinated coffee.

A Hershey’s special-dark bar has 20 milligrams of caffeine, about the same as half an ounce of espresso. Chocolate also contains theobromine, another stimulant that can increase heart rate and sleeplessness.