Marital Code: Why do people feel depressed after sex? After a self-forgetting and passionately exciting sexual encounter, most people may feel as if they are floating on clouds, with an indescribable sense of satisfaction spreading through their body. However, some individuals experience a drop in mood after reaching the peak of excitement. Brian Alexander, a sexology columnist for the American MSNBC website, refers to this phenomenon as "post-coital tristesse." This originally comes from a Latin word used to describe a "nameless sadness that occurs after sex."