Rather than feeling inadequate if you're rarely in the mood, sex therapist Dr Sandra Pertot explains why for many women a low libido can be perfectly normal

Think of any sex scene in the movies - how does the woman play her role? Almost invariably, she is hot for sex, easily aroused, passionate, satisfyingly orgasmic. Often, the woman is the seductress, the initiator, sometimes even predatory. Over the last three decades, this concept of the enthusiastically sexual female has replaced the more traditional view of the demure woman who has to be seduced rather than admit openly to sexual desires.

Think of any sex scene in the movies - how does the woman play her role? Almost invariably, she is hot for sex, easily aroused, passionate, satisfyingly orgasmic. Often, the woman is the seductress, the initiator, sometimes even predatory. Over the last three decades, this concept of the enthusiastically sexual female has replaced the more traditional view of the demure woman who has to be seduced rather than admit openly to sexual desires.

Society's view of female sexuality has changed and women now have the right to desire and enjoy sex as much as men. The development of the mass media has meant that scenes of erotic, passionate sex are now a feature of everyday life. But if women are now more liberated sexually, why are so many women unhappy with their sexuality?

The problems that people bring to a sex therapist are varied. Women worry about why they take so long to become aroused, men are concerned that they can't last long enough. For all this variety, the largest number of people seeking sex therapy are women who rarely feel any need or desire for sex. Sex researchers in the last decade have found that anywhere between one-in-five to one-in-three women complain of lack of interest in sex at some stage in their lives; for some, low libido is lifelong.

Often, women begin to outline their problem by stating, "There must be something wrong with me - I never feel like sex." It's the phrase "something wrong with me" that has caught my attention over the years. As the women cry in their distress, they reveal their fears that they must be deeply flawed in some way for not having the hot and urgent sex drive that they believe everyone is supposed to have.

In a recent survey in the US, 43 per cent of women and 31 per cent of men identified themselves as having one or more sexual problems. Among women, 33 per cent complained of low sexual desire, 24 per cent reported an inability to come to orgasm, and 14 per cent stated that they experienced pain during sex. For men, the most frequently reported problem was premature ejaculation, accounting for 28 per cent of complaints, while 15 per cent rated themselves as lacking interest in sex, and 10 per cent said they had problems attaining or maintaining an erection.

Some researchers have criticised this study because the problems were identified by self-rating rather than clinical evaluation, but it is precisely this aspect of the survey that intrigues me. If one-in-three women believes she is not as interested in sex as she should be, and one-in-four men doesn't last as long as he thinks he should, which of the following is more likely: that we have a major epidemic on our hands? Or that many in this self-selected group aren't dysfunctional but are either variations on the norm or comparing themselves unrealistically with an ideal?

Perhaps if the new, hot and happening representation of sex in general and women in particular had been confined to the domain of fiction, the erotic-movie version of sexuality would have remained a fantasy. However, support for this top-performance level of sex as an achievable norm has come from an authoritative source: sex therapy.

One exercise I often do when training sex therapists involves asking them to describe what normal sexual frequency is. Typically, the answer is: whatever is right for the individual. Then I ask how they would describe someone who only rarely desires sex, or a couple where one partner wants sex twice a week and the other once a month. Is one person closer to "normal" than the other? How would they, as sex therapists, go about helping this couple achieve sexual harmony? Which person is under more pressure to change? Despite the standard answer from therapists that this couple suffers from mismatched libidos and that both people are "normal", the pressure in therapy is most commonly on the person with the lower sex drive to pick up the pace.

There is no doubt that sex therapy began in the 1970s with very honourable intentions. Those of us who were around at the time really believed that by teaching people how to do sex better, we would eliminate the sexual dissatisfaction that plagued so many marriages at the time.

While this approach has helped many people over the years, it has had some unfortunate consequences. It set up the notions that good sex is about what you do and that sex is a series of behaviours leading to arousal and orgasm. It also means that people who are able to reach the goal of the sex-therapy programmes are regarded as successes, and by default those who can't are sexual failures.

Libido didn't get a mention at all in the early years. The view was that if people knew how to do sex properly, they would enjoy it and therefore want it more.

Early sex therapists were openly hostile to the notion of differences between the sexes. Time and again, sex researchers and therapists strongly proclaimed the view that any differences were quite insignificant and by far outweighed by the major similarities between male and female sexuality. The model that was adopted by sex therapists as the ideal standard was essentially the male stereotype of regular and persistent physical sex drive, easy arousal, prolonged intercourse, strong orgasm, and a delight in sexual experimentation and variety.

Problems with this ideal picture began to show in the 1980s when, after women became more confident of their ability to orgasm, men had been educated in the importance of foreplay, and couples strived to bring variety into their sex lives by embracing techniques such as oral sex, we found that there were a lot of women who still didn't feel any strong physical interest in sex. There were some who did in the early stage of a relationship but found that it diminished over time, leaving the woman wondering what was wrong with her, and the man wondering why he was no longer sexually attractive or, perhaps, fearful that he had been conned.

Susan and Paul are typical of the couples who consult a sex therapist about female low libido. They have been married for nine years, have two children, and Paul works full-time and Susan works varying hours as an office temp. In the early years of their relationship, they had similar levels of sexual desire and both found sex satisfying. Susan noticed that her sex drive slowed down a little once they moved in together, but it took a definite dive once the children came along. Paul is the main initiator of sex, and often Susan feels she just can't be bothered. However, most of the time, if she can get past that, she can get aroused and come to orgasm. Paul is confused: if she enjoys it, why doesn't she want it? When should he approach her? Susan says that sex is important to her but it often feels more of a hassle than it's worth. "What's wrong with me?" she asks.

While some cases of lack of interest in sex can be linked to specific problems such as life stresses, psychological conditions such as depression, medical problems such as back injury or arthritis, or merely relationship conflicts, in most cases there doesn't seem to be any identifiable pathology to account for the woman's low libido. The response of sex therapists to this situation has been to write enthusiastic books that claim to have the latest treatment that will help a woman boost her libido, become a sex goddess or soar with ecstasy so that she can experience physical desire and the passionate sex life any woman should be capable of. And if these behavioural strategies don't work, pharmaceutical companies are now investing huge amounts in developing testosterone therapies. As a result, one day there may be a pill available that will boost a woman's flagging libido.

Paradoxically, although sex therapists emphasise the importance of validating individual differences in sexuality, the end result of current attempts to solve the "problem" of female low libido has been to blur them. We seem to be assuming that because some women have a strong libido, or like a range of sexual techniques, or want orgasm with every sexual encounter, then all women should. This assumption means that women who don't feel this way must surely have something wrong with them, and, in this way, modern society is just as rigid and judgemental about sexuality as Victorian England was - it's just that the values have been reversed.

If, on the other hand, it is acknowledged that sexuality varies in the same way that all other human characteristics do, and that there are differences between the sexes which, while not absolute, nevertheless mean that there is a difference in the normal range for men and women, the "problem" of female low libido reduces dramatically. Thus, if instead of asking, "what's wrong with me - I don't have a strong libido?", the question becomes, "what helps me to feel like sex and enjoy the experience?", the range of sexual realities can be revealed without judgement.

Sex drive is anything that helps a person decide that sex is a good idea. Perhaps it is having sex initiated by soft, tender touch rather than direct sexual stimulation, or it may be a feeling of emotional closeness to the partner. It can be a thinking process ("it's been a while, we're a bit distant, tonight's a good night, let's do it"), or it can be environmental (privacy, comfort, time away from routine).

The decision to have sex is also influenced by what the woman feels is expected of her. Good sex can be brief and sensual or prolonged and passionate. It can be an expression of emotional connection, so words such as "quiet", "still", "gentle", "accepting" and "tender" reflect the mood, or it can be the more stereotyped sizzling and passionate. Feeling locked into a specific type of sex can be enough to cause the woman to prefer to roll over and simply go to sleep.

The downside of this approach is that, because people have different abilities in sex as with everything, even if you desperately want to perform like an erotic-movie star, you may not be able to do it.

At the same time, the chances of you having a serious sexual dysfunction are small, and you can achieve a satisfactory sex life if you just trust yourself, talk to your partner, and appreciate what you can do together, rather than bemoan what you can't.

'Perfectly Normal: A Woman's Guide to Living with Low Libido', by Dr Sandra Pertot (Rodale, £10.99)

'Sex isn't important'

Hilary Moss is 35 and has been with her partner for five years. She believes that she has a naturally low libido

The first time I had sex, I was 22 - much older than my friends were when they lost their virginity. It was with a man that I liked a lot, and I think I somehow expected the earth to move, even though I'd never had an orgasm before. It was a pleasant experience, but I didn't have an orgasm. We were together for a few months, then it fizzled out. During my twenties, I had two or three relationships with men and some long periods of being single. I discovered that I could have an orgasm, though, to be honest, it was a bit of an effort. I always felt slightly under pressure to show that I had had a good time.

I've talked to friends about this and, compared with them, I seem to have a low libido. That's just how I am and I accept it, but I feel a bit left out when they talk about sex or complain that they haven't had it for ages and feel desperate. I've never missed sex during the times when I've been on my own, have masturbated only a few times in my whole life, and sex has never seemed a very important part of my relationships. I also think that I haven't let it affect my judgement about men, so maybe I have an advantage in that way.

When I met my current partner, I fell head over heels in love. The sex was different, and I wanted to have sex with him a lot. That lasted about a year, and then it became less and less frequent. We've been together five years and, if I'm honest, I wouldn't mind, physically speaking, if we never had sex. I never feel a great urge to do it. I like the closeness and I don't want our relationship to suffer. And I'd like to have children. We have sex maybe once every few weeks. It's not enough for him, I know, but it is as much as I can manage.

Need to know

* This week, researchers in Massachusetts reported that the contraceptive pill may cause long-term or even permanent loss of libido. A study of 125 women found that Pill-takers had higher levels of sex hormone binding globulin (SHBG), a substance that blocks the effects of the desire-driving hormone testosterone. After six months, participants who stopped taking the Pill still had about twice the normal SHBG levels, as was the case for many after a year.

* Zinc is involved with the production of over 200 proteins and enzymes, and the hormones it produces are essential for genital function. Found in pumpkin seeds and oysters, it has been used to treat infertility. It is also an ingredient in the female Viagra-like pills and the Chinese-medicine herbal aphrodisiac, horny goat weed.

* The antioxidant effect of strawberries is said to help the libido. Cinnamon's stimulating scent has also long been linked to sexual performance. Ginger has a high zinc count, as well as a warming effect on internal organs that improves circulation to the genitals.

* Testosterone, the male sex hormone, influences parts of the brain controlling sexual thoughts and motivations. Several patch and injection supplements are already privately available to women, but boosting female testosterone is controversial, possible side effects ranging from facial-hair growth to deepening of the voice and oily skin. Women trialling testosterone report enhanced arousal and orgasm, but so far it has only been tested on postmenopausal women.

* Dopamine is one of the chemicals the brain produces when we fall in love, and dopamine levels have been linked to libido. Patches mimicking the smell of dopamine are said to increase libido by working on the brain - the body's largest sex organ.

* The UK Family Planning Association says that other lifestyle factors, including stress, alcohol intake and whether you have children, can all affect libido. Sex therapists at Relate have said that women's sexual desires are affected by relationship issues as much as by chemical and physical ones.

Gillian Murdoch