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In their recent analysis, Ueda et al¹ found decreases in sexual activity among US individuals aged 18-44 years between 2000 and 2018. The percentage of 18- to 24-year-old men who were sexually inactive in the past year increased from 18.9% in 2000-2002 to 30.9% in 2016-2018. Similar trends in sexual inactivity appeared among individuals aged 25-34 years but not among individuals aged 35-44 years.

Ueda et al¹ built on several previous studies^2-4 that found decreases in sexual frequency and increases in sexual inactivity among US adults.² The percentage of British residents sexually inactive in the past month also increased between 2001 and 2012.³ In addition, sexual activity is also less common among US adolescents; 39% of youths in ninth to twelfth grade had participated in sexual intercourse in 2017 compared with 53% in 1991.⁴ These shifts mirror changes in the birth and pregnancy rates in these age groups; the teen pregnancy rate has decreased precipitously, and the birth rate among individuals aged 20-29 years has also decreased.

Thus, there is a body of evidence suggesting that sexual activity has decreased in Western countries, particularly in the past 2 decades.¹ The more difficult question to answer is why this trend has occurred. Understanding the reasons behind the trend may help address whether it is concerning, neutral, or positive. In my view, there are 2 primary possibilities for why sexual activity has decreased.

First, adolescents and young adults are taking longer to grow to adulthood. This includes the postponement of not just sexual activity but also other activities related to mating and reproduction, including dating, living with a partner, pregnancy, and birth. However, these reproductive trends have not occurred in isolation; instead, they are part of a broader cultural trend toward delayed development. For example, adolescents in the 2010s were also less likely to drive, drink alcohol, go out without their parents, and work at paid jobs compared with adolescents in previous decades.⁴ The employment rate of young adults, particularly young men, has also decreased. Ueda et al¹ found that sexual inactivity was more common among men without full-time employment. As employment rates have decreased, so has sexual activity. In addition, fewer young adults are living with a partner (married or unmarried), and more are living with their parents than in past decades. Adult activities reinforce each other. It is more difficult to date and engage in sexual activity when not economically independent of one’s parents. It remains to be seen whether these cohorts of young men will catch up to previous cohorts in employment and other adult activities; if so, their level of sexual activity may also catch up.

However, the trend toward growing up more slowly does not explain why sexual frequency has also decreased among older and married adults. In this case, other cultural forces must be at work. It seems unlikely that economic or employment issues could explain the trends; the decrease in sexual activity was roughly linear between 2000 and 2018, whereas economic trends during this period were curvilinear (with economic growth, a recession, and then a return to economic growth). In addition, employment rates in older age groups have not decreased as they have among young men. The increasing availability of pornography may play a role; however, because those who watch pornography are more sexually active, not less, this explanation is difficult to support with individual-level data. Changes in attitudes about sex are also unlikely to explain the trend, with attitudes toward premarital sex becoming more accepting not less.

That leaves another substantial change that has occurred since 2000: the growth of the internet and digital media. Although internet sites and social media should theoretically make it easier to find new sexual partners, time spent online has also displaced time once spent on face-to-face social interaction.⁵ Even when individuals interact face to face, mobile technology such as smartphones may interfere with the satisfaction that people derive from in-person interaction .⁶ The neologism phubbing describes a social interaction in which one partner pulls out his/her phone, thus snubbing the other partner. This behavior may be especially problematic in romantic relationships, in which it is associated with lower relationship satisfaction.⁷ Between the 24-hour availability of entertainment and the temptation to use smartphones and social media, sexual activity may not be as attractive as it once was. Put simply, there are now many more choices of things to do in the late evening than there once were and fewer opportunities to initiate sexual activity if both partners are engrossed in social media, electronic gaming, or binge watching.

Given the impossibility of randomized clinical trials in cultural change research, it is difficult to determine whether either, both, or neither of these explanations for the decline in sexual activity are correct. However, it seems clear that the trend toward less sexual activity has not occurred in isolation; it coincides with other substantial cultural shifts, such as the slowing of the developmental trajectory and the increase in time spent on electronic media.

Published: June 12, 2020. doi:10.1001/jamanetworkopen.2020.3889

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Twenge JM. ÌÇÐÄvlog Open.

Corresponding Author: Jean M. Twenge, PhD, Department of Psychology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-4611 (jtwenge@mail.sdsu.edu).

Conflict of Interest Disclosures: Dr Twenge reported receiving personal fees from Verizon and from Jana Partners outside the submitted work and receiving royalties from Atria Books from sales of the book iGen: Why Today's Super-Connected Kids Are Growing Up Less Rebellious, More Tolerant, Less Happy—and Completely Unprepared for Adulthood.