The desire and ability to make love can vary during an individual’s lifetime and during a couple’s relationship. In purely physical terms, men are at their most potent in late teenage years, whereas women reach their peak of sexual enjoyment around the age of 35 years. However, men and women can find that both the desire for sex and performance can be adversely affected, even lost completely for a time, by various events and situations; for example, stress at work, family problems, illness, a new baby or a death in the family. These factors may cause men to become temporarily impotent, that is, find it impossible to get, or keep, an erection; and women may find intercourse painful and orgasm impossible, even with prolonged stimulation.Only a small minority of sexual problems are caused by disease (such as diabetes mellitus) or hormonal disorder. If a man is impotent for example, the root cause is not necessarily a diminished production of testosterone. It is more likely that the difficulties are a sign that more attention should be paid to resolving hidden emotional problems.The same holds true for so-called ‘frigidity’. This term is usually used to describe a person who is totally unable to achieve sexual excitement despite adequate stimulation. Frigidity is most commonly applied to women, but men can be frigid as well. In the majority of cases, the cause has to do with an apprehension of anything that has to do with sexual matters.AgeingThe process of ageing can have both a psychological and physiological affect on a couple’s desire and ability to perform sexually. The body’s muscles become more slack, blood is coursing more slowly through arteries that have become increasingly constricted and a couple may tire much more quickly. In short, sexual response is less acute than previously and may be mirrored by a decline in sexual interest. The menopause in women, usually occurring between the ages of 45 and 55, brings with it profound physical changes. The body’s hormonal balance alters and a woman’s periods become irregular before menstruation ceases altogether. Lower levels of oestrogen cause the tissues of the vagina to become drier, and if insufficient lubrication is produced intercourse can be painful unless an artificial lubricant is used. The woman may also experience dramatic swings of mood, disturbed sleep and hot unpleasant sweating (‘hot flushes’). Hormone replacement therapy effectively relieves the worst discomfort caused by the menopause in a large number of cases, but can obviously do little to alleviate distressful psychological symptoms. Most commonly these take the form of the woman feeling that now she can no longer bear children, she has also lost her sexual attractiveness: she ceases to feel ‘eligible’ for sexual relations. This is particularly true of women who have been brought up to believe that sex should be solely procreative, rather than a recreational release of tension and a way of showing love to a partner.Men approaching late middle age may have their own problems to face up to. Unfulfilled ambitions, a feeling that opportunities for career advancement have been missed and worries over diminishing potency can all lead to a lack of self-confidence and affect sexual performance.Barring physical disability, however, there is no reason why a couple should not enjoy a rich and rewarding sex life until the end of their years. Indeed, growing older brings with it its own particular pleasures. It is a time of reassessment and also renewal, a time when a couple cannot only take stock of the preceding years, but revitalize their relationship and grow closer together.AphrodisiacsHuman beings have always looked for nostrums and elixirs that will increase or create sexual desire and potency. Most of the famous ones are frankly symbolic and are supposed to work by ‘sympathetic magic’. For example, asparagus, rhinoceros horn and lampreys are said to resemble the penis; mandrake root and ginseng, which have also been used as aphrodisiacs, are believed to symbolize Man himself..Oysters and figs, on the other hand, are thought to resemble an open vagina. The belief was that if these things were eaten, they would have a magic effect – and, of course, if you believe they will, they can be miraculous in their effect. A romantic dinner of asparagus and oysters may well revitalize a dull relationship, but it will owe more to the effort put into the situation by the couple involved than to the ingredients of the dishes.There are exceptions, however. Alcohol, for example, can have an aphrodisiac effect because it relaxes inhibitions enough for a tense, tired or nervous person to enjoy sex. Too much alcohol can have the opposite effect and leave the man unable to have an erection. Another substance that is often thought of as an aphrodisiac is Spanish fly, or cantharides. In fact, it is an irritant that acts on the urethra. It can cause a prolonged erection in the man and a sensation of heat around the urinary and genital tracts in the woman. Neither of these effects is particularly pleasant and neither feels at all sexy.Without a doubt the best aphrodisiac is a loving and attentive partner who knows enough about sex in general, and you in particular, to make sexual intercourse both exciting and satisfying.