DOPAMINE—THE PLEASURE HORMONE We subscribe to Pandora Music and every few days change stations so we can listen to newer artists we wouldn’t usually dial up. This week I heard the 20-year-old Grammy Award winner Billie Eilish sing her song “Oxytocin,” in which one of the lines is: “You know I need you for the oxytocin.” Well, it made me wonder what the heck is oxytocin; is it one of the drugs we should stay away from because it’s addictive? I found out that it’s actually one of several “feel-good hormones.” Now, I wanted to know more about these jovial...