Aging and Sexuality

Normal Sexual Response Cycle

It is important to understand the normal sexual response cycle in order to better understand the age associated changes, impact of diseases and drugs on sexuality of elderly. Willian Masters and Virginia Johnson described the model of normal sexual response consisting of four phases namely Excitement or arousal, Plateau, orgasm and resolution (Masters & Johnson, 1996). Kaplan and others added another phase called desire. In this model, sexual cycle is not a linear process but rather a waxing and waning pattern of sexual arousal which may culminate in orgasm depending on the host factors (Agronin, 2010).

Desire, the first stage is characterized by psychological urge to seek out and respond to sexual interaction. Limbic system of the brain, particularly the hypothalamus is responsible for desire. Testosterone is essential for the adequate desire to be maintained in both the sexes. Desire is closely associated with, and is often inseparable from arousal, the second stage of sexual response. Arousal is the physiological process of sexual excitement. In both the sexes, arousal is triggered by sexual fantasies, thoughts or direct sexual stimulation and is mediated by parasympathetic nervous system. In men arousal leads to penile erection, where as in women it is characterized by clitoral enlargement, swelling of other genital tissues and breast and vaginal lubrication. Plateau, the third stage relatively short lasting and is characterized by sense of impending orgasm. Orgasm is characterized by euphoria in both the sexes. There are multiple contractions of seminal vesicles, vas deference in men leading to ejaculation of seminal fluid and multiple contractions of vaginal and pelvic muscles in females. In men, orgasm is brief, lasting for few seconds and usually happening only once before the refractory period, whereas, in women orgasm may last for many seconds to minutes and multiple orgasms are possible. Resolution is a state of relaxation which follows orgasm and it is a refractory period. Refractory period is longer in males than females (Meston, 1997; Agronin, 2010; Tekkalaki, 2015).