After Sex Cuddles and Falling Asleep Shows You're In Love

Research carried out by evolutionary psychologists at the University of Michigan and Albright College in Pennsylvania have established that those who tend to fall asleep first after sex have a greater affection for their partner because "the more one’s partner was likely to fall asleep first after sex, the stronger the desire for greater partner expressions of affection and emotional bonding after sex."

In their published paper, "Tendencies To Fall Asleep First After Sex Are Associated With Greater Partner Desires For Bonding And Affection", Daniel J. Kruger and Susan M. Hughes explore the fundamental difference between men and women in relation to emotional needs associated with sex: women look for a long term partner who they can depend on when bringing up children. Men on the other hand "have less of an incentive to commit to long-term monogamous relationships" because they prefer to keep their options open. 

So when attempting to understand the level of desire and bonding between men and women, research has established that post sex behaviour is the most important aspect of a sexual relationship.

Men who prefer not to engage in post sex conversation and promises could also risk being dumped if the woman finds it unattractive. So "hastening sleep onset may evade this adverse effect." 

Kruger and Hughes also explain that men and women's "desires for ... emotional bonding, physical affection, and communication were higher when their partners 'had greater tendencies to fall asleep first after sex.'  

In the men's department, the study suggests that one of the reasons why men fall asleep before women could be because they are more exhausted, having performed more actively during sex. Yet the stereotype of men generally falling asleep first is disputed with some staying awake longer to coerce their partner into more sexual activity or simply to make sure that their partner doesn't leave them for someone else. 

The research carried out involved anonymous questionaires from 456 undergraduates (295 of which were females and 161, male).