High levels of testosterone during sex are related to a reduced desire to talk to one’s partner afterwards, according to a study published in the Journal of Social and Personal Relationships.

“Pillow talk,” communication with one’s partner that occurs immediately after sexual activity, is thought by relationship researchers to be important for building intimate emotional bonds. Couples who engage in more post-sex communication have been found to be more satisfied with their sex lives and with their relationships in general.

However, this type of communication can also be seen as risky, particularly in new or casual sexual relationships, because revealing too much about one’s feelings may put one at greater risk of being hurt. Testosterone, a hormone found in large quantities in men’s bodies and in smaller amounts in women’s bodies, is closely linked to sexual behavior. This hormone has also been theorized to affect people’s motivation to form affectionate bonds with their partners.

A team of researchers led by Amanda Denes, of the University of Connecticut, conducted a study aimed at understanding how testosterone affects post-sex communication. A sample of 253 sexually active university students had their testosterone levels measured, and kept diaries of their sexual experiences over a period of two weeks. In these diaries, the study participants recorded the kinds of communication they engaged in with their partners after each experience, as well as their feelings regarding that communication.

Among both women and men, higher levels of testosterone were related to greater regret about post-sex communication. The researchers used data modeling techniques to determine that testosterone levels could explain differences in people’s perception of the balance between the risks and rewards of post-sex communication, which in turn could explain differences in the types of communication they engaged in.

People with higher testosterone levels perceived their communications as having been riskier, and having fewer potential benefits. In turn, people with negative perceptions of the value of pillow talk not only engaged in less post-sex communication, but also talked less about personal emotions and were more likely to have said negative things to their partners.

The authors of the study conclude that physiology, specifically levels of testosterone, impact communication with sexual partners among both men and women. Because post-sex communication is thought to be important for building and maintaining intimate relationships, high testosterone may interfere with these goals.

Since factors like age, health, and exercise levels can impact testosterone production, these factors may in turn impact communication and relationship formation. Although higher testosterone may increase sex drive, it may also lead to more ambivalence and regret about the communication that goes on afterwards.