Whoever said that 'life begins at 40' was probably right, as far as women and sex are concerned. A Brit survey has found that women in their 40s have a better time in bed than at any other stage of their life. It also found that more than a quarter of married women admitted having had an affair, compared with an estimated 18 per cent of husbands. In the survey of 2,000 women, it was found that those in their 40s are less self-conscious about their bodies and as a result are more confident between the sheets. Up to 80 per cent said that they are now more adventurous with their partner than during their 20s, with 60 per cent saying they feel more assertive. According to experts, this is the age when females hit their ''sexual confidence'' peak - they know what they want in the bedroom and they are not afraid to ask. On the other hand, a fifth of women under 30 say they often merely pretend to be satisfied in bed, compared with just seven per cent of 40-somethings. Researchers also found that 68 per cent of women in their 40s are fully aware of which love-making technique gives them the most pleasure, and more than half say they are not too embarrassed to ask. Up to 58 per cent say they have the best sex when they are married, often because they are more experienced. They also tend to have fewer worries than during their 20s or 30s, either about work or children, so they can properly relax in the bedroom. Well over 90 per cent of women insisted that fidelity was essential in a long-term relationship - which made the number admitting to affairs so surprising. Only five per cent of the married women who admitted being unfaithful said it was when they had the best sex. By comparison, 58 per cent said the best sex they had ever had was with their husband. The survey also showed that the average woman over 40 has had five sexual partners in her life - compared with nine for the average 30-something. "The real sexual adventure begins when the children are older or have left home and women have the body confidence and experience to enjoy sex more than ever before," the Daily Mail quoted Nicola Down, editor of Top Sante magazine, which carried out the research, as saying. "Our survey clearly shows that married women in their 40s have the best sex lives. So it's sad that eight out of ten women think society and younger people in particular don't have a positive image about older women when, in truth, they are the ones worldly enough to enjoy a wonderful sex life," she added.