Just under a third of people aged over 70 are sexually active, a survey has revealed.

at the University of Liège in Belgium and her colleagues are interested in the sexual activity of older people and how this relates to their well-being.

To better understand the prevalence of sexual activity among this age group, the researchers led a survey of 511 people who lived in Belgium and were aged 70 or over. Of the participants, 200 were in their eighties and 29 in their nineties.

Thirty-one per cent of the participants reported being sexually active in the past year. This was defined as engaging in any kind of sexual practice, including vaginal intercourse, masturbation, oral sex and anal sex.

Of the remaining participants, 47 per cent said they had been involved in acts of “physical tenderness” with a partner, mainly kissing and cuddling, in the past 12 months.

Sexual activity was more common among people who had a partner and a “permissive attitude” to intimacy, . Those who were relatively younger than the other participants and didn’t have a disability were also more likely to be sexually active.

Overall, 74 per cent of the sexually active participants said they were satisfied with their sex life, according to Cismaru-Inescu. Of those who weren’t sexually active, nearly 60 per cent said they, too, were content with this level of intimacy.

“When we talk about older adults, we just have this idea that, ‘oh, these are just grannies and grandpas who like cooking and going for a walk’,” says Cismaru-Inescu. “We don’t even think that they could have a sexuality.”

The World Health Organization has called for sexuality to be recognised as an aspect of well-being across all age groups. But in , Cismaru-Inescu and her colleagues reported how healthcare professionals lack knowledge and communication skills when it comes to sexuality among older people.

“Sexuality in later life exists,” says Cismaru-Inescu. “This is pure evidence and it can’t be denied.”

“So, at different levels, we have to do something, because healthcare professionals don’t know much about it, and nursing home staff need to recognise that people want some time alone, meaning not just walking into their rooms but letting them have some privacy,” she says.

The average age is rising across populations around the world – a demographic shift that not only poses conundrums for social welfare systems, but may also pose a significant challenge to energy systems and efforts to rein in climate change.

Hossein Estiri of Harvard University and Emilio Zagheni of the Max Planck Institute for Demographic Research, in Germany, have found that energy use increases as we get older, and not just because we accumulate more wealth through life. A greying population could mean a greater proportion of society with high energy consumption levels, their study suggests.

On average, children’s energy consumption climbs as they grow up, before dipping slightly when they leave home, their analysis of US data showed. Consumption then rises when people hit their thirties, peaks at 55 years old, and then briefly drops before beginning to climb again.

The study controlled for factors such as income, local climate, and the age, type and size of a person’s home. The increase in energy use throughout lifespan seems to be down instead to lifestyle and how our needs change as we age.

More of everything

Why does demand surge so much in our thirties? “We need more of everything. More space. We need more: a bigger TV, we now need two fridges,” says Estiri.

The study found that in warmer parts of the US, unlike in colder ones, energy use intensifies in people over the age of 65 – probably for air conditioning. This suggests that climate change and an ageing population may be increasing the effects of each other.

Heatwaves have and are expected to become more frequent due to global warming. More older people using more energy to keep cool could contribute to more warming, until that energy supply is made fossil fuel-free.

“This confluence of population, ageing and climate change on energy demand is really important to start thinking about,” says Estiri.

Benjamin Sovacool at University of Sussex, UK, says the work shows the importance of demographics when it comes to cutting carbon emissions. Most climate change mitigation modelling assumes people’s energy consumption either stays the same or only makes small changes over time.

“This study directly challenges that entire body of research by forcing it to grapple with the sheer temporality and complexity of the consumption of energy,” says Sovacool. “Households do not behave in ways easy to predict or comprehend.”

The new work combined two decades worth of data from US households , which surveyed between 6100 and 12,100 households in four waves.

The data was then used to build a model of a virtual cohort of individuals and how energy use varied across 17 different age groups between 1987 and 2009.

Catherine Mitchell of the University of Exeter, UK, says the research could have important ramifications for policymakers. “What the paper says is that there is a lot of work about how buildings use energy, but probably not enough about the how the people in them use energy,” she says.