More Evidence that Fathering Affects Men at a Biological Level

Friday Sep 7, 2012

A new study has found that co-sleeping with babies has a biological effect on fathers. Specifically, the study, led by Notre Dame anthropology professor, Lee Gettler, found that fathers who slept on the same surface as babies had lower evening levels of testosterone and also a greater decline in testosterone over the course of the day compared to fathers who did not sleep on the same surface as their babies.

This paper is part of a larger study of Filipino men. In a previous paper, Gettler and his colleagues reported that becoming and father and being involved in infant care led to reduced levels of testosterone in men.

These results are consistent with previous research has shown that having a pregnant partner, becoming a father and caring for babies have an impact on men's levels of prolactin, cortisol and testosterone.

It should be noted that parents and babies sleeping on the same mat, mattress or pad (usually on the floor) is very common - culturally normative - in the Phillipines. In fact, 92 percent of the fathers in this study reported that they sleep on the same surface as their babies.

Read the full text of the journal article Does Cosleeping Contribute to Lower Testosterone Levels in Fathers? Evidence from the Philippines.

To read more about theimpact of fatherhood on men's hormones.