The art of pillow talk is understood to maintain intimacy and security in a relationship after a session of coitus. Assistant Professor Amanda Denes was interested in the disparity of how people opened up to their sexual partners during a scientifically named 'post-coital time interval.' She writes:
For some, saying "I love you" for the first time after sex brought the relationship to the next level. For others, the same disclosure led to regret for having confessed one's sentiments too soon…Why such different experiences? Why were some people sharing their innermost feelings, even when they knew the relationship had not yet reached that level? What effects would these post-coital disclosures have on relationship satisfaction?
Denes found that pillow talk is linked to the female orgasm and its connection with oxytocin - the love/memory/bonding hormone production. She found that women who had orgasmed during sex were more likely to open up to their partners than those who did not orgasm.

Is this the reason for all the pillow talk sessions you've had to have?