The tendency to fall asleep first after sex is associated with greater partner desire for bonding and affection, a new study has found.

For the recent study by evolutionary psychologists at the University of Michigan and Albright College in Pennsylvania examined 456 participants, who completed anonymous online surveys assessing experiences and desires with one's partner after sex.

Participants then indicated "who falls asleep after sex?" and "who falls asleep first when going to bed not after sex?"

"The more one's partner was likely to fall asleep after sex, the stronger the desire for bonding," Newswise quoted Daniel Kruger, lead author of the study as saying.

The researchers found that participants whose partners nodded off immediately after sex had stronger desires for post-coital cuddling and chatting.

"Falling asleep before one's partner may be a non-conscious way to foreclose on any commitment conversation after sex," Susan Hughes, co-author of the study, said.

The study has been published in the Journal of Social, Evolutionary, and Cultural Psychology.