As many as four in ten young adults are in the midst of a year-long dry spell when it comes to sex.

A nationally representative survey in California shows that in 2021, 38 percent of people aged 18 to 30 reported having no sexual partners in the prior 12 months, up from 29 percent in 2019. 

Older adults were far less likely to report a year-long period of abstinence. In 2021, that rate was about 20 percent, up slightly from the 18 percent reported in 2020. 

Researchers say that the rising cost of living after the pandemic has meant young people are living with their parents longer and spending more time online - reducing the opportunity for sex. 

The latest tally comes from the California Health Interview Survey (CHIS), the largest state health survey in the US.

Unlike their younger counterparts, older adults have not seen the same drop in sexual activity. The rate at which adults 31 to 64 reported no sexual partners in 12 months has hovered around 17 percent over the past decade.

Experts believe high rates of abstinence, wanted or unwanted, reflect changing attitudes toward long-term relationships and marriage coupled with precarious economic times and an embrace of digital distant relationships.

Dr Lei Lei, a sociologist at Rutgers University who has studied declining casual sex rates, said: 'The new generation of young adults became more individualistic and less social in real life, but more involved in social media and online gaming networks.