Pleasurable sex heavily depends on the brain, which releases hormones that support sexual pleasure and interpret stimulation as pleasurable. One 2016 study suggests that the brain could be the most important sexual organ. The author found that orgasm is a heightened state of sensory awareness that can trigger a trance-like state in the brain. In this article, we examine the effects that sex has on the body and the brain, as well as how these effects make sex feel good. We also take a look at why sex might not feel good. Effects of sex on the body In the 1960s, sex researchers William Masters and Virginia Johnson identified four distinct phases of sexual arousal, each with unique effects on the body.