Sexual arousal is the arousal of sexual desires in anticipation for sexual activity. Things that precipitate human sexual arousal are colloquially known as turn-ons.

Human sexual arousal

The things which people find sexually arousing vary considerably. They may be physical or mental in nature.

Most people are sexually aroused by a physical contact from another person, especially if the other person is in an intimate relationship, and especially if the contact is in an erogenous area, and even more so if it is accompanied with the anticipation of an imminent sexual activity.

In addition, some people may find nudity, erotica and pornography sexually arousing, though what aspect different people find arousing will vary. Most heterosexual males are visually stimulated by female nudity or partial nudity, while some heterosexual females are stimulated by the state of romance with their partner. According to the marital and sex therapist, David Schnarch, intimacy, the honest portrayal of the two people joining in the sexual act, may lead to a heightened state of passion in sex, including sexual arousal. Such sexual arousal may not lead to an actual sexual activity, beyond a mental arousal. In a 2004 study at Northwestern University, the female participants (both heterosexual and homosexual women) became sexually aroused when they viewed straight as well as lesbian erotic films. Among the male participants, however, the heterosexual men were turned on only by erotic films showing women; the gay males were aroused only by films showing men. The study's senior researcher said that women's sexual desire is less rigidly directed toward a particular gender, as compared with men's; and women's desire is more changeable over time.

When sexual arousal is achieved by or dependent on the use of objects, it is referred to as sexual fetishism. Sexual arousal may also be assisted by a romantic setting, music, or other soothing situations.

Given the right stimulation, sexual arousal in humans will typically end in an orgasm, but may be pursued for its own sake, even in the absence of an orgasm.

Unlike most animals, human beings of both sexes are potentially capable of sexual arousal throughout the year; therefore, there is no human mating season.

Physiological changes

Sexual arousal for a man is usually indicated by the swelling and erection of the penis. This is usually the most prominent and reliable sign of sexual arousal in males; however, adolescent males experience 'non-sexual' erections stemming from high levels of testosterone.

In a woman, sexual arousal usually leads to vaginal lubrication in anticipation of sexual intercourse.

Sexual arousal causes different physical changes.

Human sexual response cycle

main: Human sexual response cycle During the 1950s and 1960s, William H. Masters and Virginia E. Johnson conducted many important studies within the field of human sexuality. In 1966, the two released a book, Human Sexual Response, detailing four stages of physiological changes in humans during sexual stimulation. These phases, in order of their occurrence, are excitement, plateau, orgasmic, and resolution.