"At climax, dopamine drops (and/or nerve cell receptors for dopamine decline, leaving your reward circuitry less sensitive to dopamine). At the same time, the neurohormone prolactin shoots up. Like most hormones, prolactin has many jobs in the body. After orgasm it acts as a "sexual satiation" substance, suppressing dopamine. Dopamine is an accelerator; prolactin is like brakes."