The Surprising Science of Pillow Talk

Post-coital interaction may be crucial to relationship satisfaction.

Posted Aug 01, 2014


However, the period of time right after intercourse—known variably as "after sex," "after play," "pillow talk," "aftercare," or "post-coital time interval"—has served mostly as fodder for stale humor about snoring husbands and eye-rolling wives (and, more recently, a risqué playground for the selfie generation).

Serious scientific attention to the topic has been scant.

In the 1950s, Kinsey’s famous report noted vast individual differences in post-coital behavior, with some individuals becoming sleepy while others become hyper-alert. In the late 1970s, psychologists James Halpern and Mark Sherman summarized a survey of more than 250 American participants in a book called Afterplay: A Key to Intimacy, in which they argued that post-sex communication should be regarded as a fundamental part of sex. Both male and female participants in Halpern and Sherman’s sample reported a wish for more afterplay than they were getting; additionally, the authors found a positive correlation between the duration of post-coital interaction and relationship satisfaction for both sexes.

The limited research conducted on the topic in the 1980s focused on gender differences, finding women generally more likely to desire afterplay than men (Elaine Hatfield et al; Denney et al).

In the 1990s and into the new millennium, studies of post-coitus shifted to focus on contraception, as various "morning after" methods were developed. Other research on post-coital interaction practically ceased during this period.

This lack of attention has been puzzling given the fact that the period after intercourse appears, on its face, to provide prime opportunity for partners to express positive sentiments and experience closeness, intimacy, and bonding—all of which are known to contribute to relationship and sexual satisfaction. In fact, the behaviors most frequently engaged in after sex, namely cuddling and kissing, have been shown specifically to relate to sexual satisfaction in both men and women (Julia R. Heiman et al).

Further hinting at the potential importance of the post-coital period is research showing post-copulatory behavior to be a highly regulated feature of the mating dance in several species. For example, the post-coital female fruit fly switches abruptly from being sexually receptive to being non-receptive. These behavioral changes are triggered by a protein inside the male fly’s semen that affects a group of neurons inside the female’s genital tract.

In humans, recent findings (Borrow and Cameron; Feldman) about the hormone oxytocin—which is released during sexual activity (as well as childbirth) and is thought to play a role in facilitating attachment and pair bonding—have provided a potential biological explanation for how after-sex interactions may act to increase feelings of safety, trust, and intimacy between partners.

Recently, a batch of new inquiries has sought to close the historical gap and map out the post-intercourse territory in more detail. Much of this current work is informed by the evolutionary framework, which predicts that post-coital behavior, to the extent that it carries reproductive value, will differ between the sexes in accordance with their differing optimal mating strategies.

Specifically, women are expected to seek and regard post-coital interaction more highly, as they have a vested evolutionary interest in pursuing stable, long-term pair bonds that will protect them and their offspring during and after pregnancy. Men, on the other hand, stand to benefit biologically from multiple short-term sexual interactions and are, therefore, assumed to be less inclined toward post-coital investment.

Consistent with evolutionary prediction, research (Hughes et al, 2004) has shown that sleeping together after sex (as opposed to getting up and leaving) is usually initiated by women and is more important to women than to men.

Likewise, a 2010 study by Susan Hughes of Albright College and Daniel Kruger of the University of Michigan found gender differences in post-sex behavior in their sample of 170 primarily young university students. Specifically, the authors looked at five post-coital behaviors: intimate talking; kissing; cuddling and caressing; professing love for the partner; and talking about the relationship. The results showed that females were more likely both to initiate and place a greater importance on all five.

Additionally, Koichi Nagao and colleagues at Toho University School of Medicine in Tokyo recently published results from a survey of more than 5,500 Japanese women about the differences between actual and desired sexual activity. Results revealed that the women desired more afterplay than they were receiving.

However, another study by Daniel Kruger and Susan Hughes produced a more complicated picture. Analyzing an ethnically diverse sample of 456 undergraduates from two Midwestern universities, the researchers found support for the notion that post-coital interaction is important for relationship maintenance. Specifically, across sexes, people whose partners fell asleep quickly were left hungrier for communication and intimacy than those whose partners stayed awake longer. However, the researchers found no differences in reported post-coital sleep onset between men and women in their sample (although men reported that women tended to fall asleep faster if sex hadn’t occurred).

Other research (Davis, Shaver and Vernon) has also shown that the decision to communicate or nap after intercourse depends on several variables other than gender. For example, attachment plays a role. Avoidant people are less interested in talking after sex; anxiously attached women, on the other hand, tend to desire more than they receive post-coitus.

Hughes and Kruger (2010) found a link between post-coital bonding activities and relationship type. Specifically, such activities were more likely to occur with a long-term than short-term partner (although this association was stronger in women).

A 2012 study of 200 American college students by Amanda Denes of the University of California at Santa Barbara has also linked post coital interaction to orgasm. Overall, participants who had an orgasm reported perceiving greater benefits and fewer risks to post-coital disclosure. In particular, women were more likely to engage in positive disclosure post-intercourse when they had had an orgasm. And positive disclosures happened more often in committed relationships: Consistent with previous research, Denes found that post-coital disclosure was linked to higher trust and intimacy in the relationships, as well as closeness and satisfaction (although the direction of causality cannot be inferred from her analysis).

More recent work by Denes and Tamara Afifi (2014) with 253 participants, (ages 18 to 45) also found that orgasm predicted more positive and deeper disclosure between partners post-coitus. Alcohol consumption, on the other hand, predicted post-coital problems, including less intentional and less positive disclosures.

The reasons for partners’ tendency to disclose more post-coitus if they had had an orgasm are not yet clear. Denes argues that individual privacy boundaries become more permeable after orgasm and that people tend to perceive less risk and more benefits in disclosing post orgasm. Another possibility is that oxytocin levels, which increase quite dramatically immediately after orgasm, contribute to this effect, through the hormone’s documented tendency to decrease stress and suspiciousness and increase trust and affiliative motivation.

Looking to explore the link between affectionate post-sex behaviors and relationship satisfaction, Amy Muise of the University of Toronto and colleagues published data recently (2014) summarizing two interesting studies: The first, a survey of 335 individuals in romantic relationships, found that the duration of post-sex affection was positively associated with higher sexual satisfaction and higher relationships satisfaction. Participants reported an average length of post-sex affection of 15 minutes. The second study, which followed 101 established couples for 21 days, found similar results, as affectionate post-sex behavior predicted sexual and relationship satisfaction—even three months later. This association was stronger for women than for men, however.

There is much left to learn about the nature and implications of post-coital interaction:

  • The findings to date have been largely based on data from American university students, which cannot be taken as universally representative. Cross-cultural data could vastly expand our understanding of the biological and social forces that interact to shape post-coital behavior and attitudes, as well as their relational implications.
  • More research is needed on the dynamics of afterplay in the gay and lesbian community.
  • In addition, the lack of experimental and longitudinal data limits our ability to draw conclusions about causality. We don’t yet know whether post-coital interaction causes, or is caused by, increased relationship satisfaction.

Still, the picture emerging from the new research appears to support the notion that post-coital interaction may serve an important function in predicting, reflecting, and perhaps facilitating intimacy and relationship satisfaction. While post coital interaction is generally valued more highly by women, it appears to benefit both sexes, and may be shaped by multiple factors other than gender, including the partners’ individual characteristics (attachment style), relationship type (long vs. short term), and sexual satisfaction (orgasm—yes or no).

Good sex, in this picture, is the kind that ends in the same way it starts—with kisses, cuddles, touching and sweet whispers.