Fewer than half of British men and women have sex at least once a week

The data show a general decline in sexual activity in Britain between 2001 and 2012, with the steepest declines among the over 25s and those who are married or living together.

There is evidence that regular sexual activity is beneficial to health and wellbeing, but a recent decline has been seen in several high-income countries in the proportion of people who are sexually active, and how often they have sex.

Little is known about these trends in Britain and the lifestyle factors associated with them.

So to explore this further, researchers at the London School of Hygiene & Tropical Medicine used data from over 34,000 men and women aged 16 to 44 years in three successive waves of the British National Survey of Sexual Attitudes and Lifestyles (Natsals 1, 2 and 3) to measure changes in actual and preferred frequency of sex, and to examine factors associated with sexual activity.

The three surveys were completed in 1991, 2001 and 2012 and reported sexual activity included vaginal, anal, or oral sex with opposite or same-sex partners.

Overall, the data show declines in people having sex between 2001 and 2012. For example, the proportion reporting no sex in the past month increased from 23% to 29.3% among women and from 26% to 29.2% among men.

The proportion reporting sex 10 or more times in the past month also fell during this time, from 20.6% to 13.2% among women and from 20.2% to 14.4% among men.

Declines in levels of sexual activity were evident across all age groups for women, and for all but the 16-24 year old age group for men, but were largest among those aged 25 and over and those who were married or living together.

For instance, the average number of times that 35-44 year olds reported having sex in the past month fell from four to two among women and from four to three among men, and the odds of reporting sex 10 or more times in the past month halved.

Similarly, among men and women who were married or living together, reported sexual inactivity in the last month was higher, while the odds of reporting sex 10 or more times in the past month were roughly halved.

Declines of this magnitude were not seen among single people, suggesting that the trend towards lower sexual frequency overall is largely due to the decline among sexually active married or cohabiting couples, say the authors.

However, the data also show that close to half of all women (50.6%) and almost two thirds of men (64.3%) said they would prefer to have sex more often, particularly those who were married or living together, which the authors say "merits concern."

People in better physical and mental health, and those who were fully employed and had higher incomes, reported having sex more often.

This is an observational study, and as such, can't establish cause. And because the data was volunteered, this may have influenced the results.

But the authors say that the changing norms around sex may affect both reported and actual sexual frequency. For example, the social pressure to over-report sexual activity may have eased, while gender equality means that women may now be less inclined to meet their partner's sexual needs irrespective of their own.

They also point out that the decline in sexual frequency appears to coincide with increasing use of social media (which has created diversions) and the global recession of 2008 (which may explain the decline both among men who are better off and those worse off).

However, given the age and marital status of the groups most affected, the "most compelling" explanation may relate to the stress and 'busyness' of modern life, such that work, family life and leisure are constantly juggled, they add.

"It is perhaps the wider implications of the decline in sexual frequency that may be more worrying," write the authors. "Should frequency of sexual contact serve as a barometer for more general human connectedness then the decline might be seen as signalling a disquieting trend. The decrease in sexual activity is interesting, as yet unexplained, and warrants further exploration," they conclude.

In a linked editorial, Dr Peter Leusink from Radboud University Medical Centre says that "as the authors point out, less frequent sexual activity is not necessarily a problem for individual health and wellbeing" and the "quantity and quality of sexual activity are not necessarily connected."

He adds "Healthcare professionals should be aware of the links between sexual health, general health, and social factors and should be alert to the possibility of sexual problems during discussions with patients. [These] findings should encourage both researchers and clinicians to start talking about sex."