Does Cosleeping Contribute to Lower Testosterone Levels in Fathers? Evidence

A previous Chinese study footnoted in this article showed that fathers had lower T than single men and married, non-fathers.

This article is a fascinating addition to the role of testosterone in males and environmental influences.  

JR

Does Cosleeping Contribute to Lower Testosterone Levels in Fathers? Evidence from the Philippines

Lee T. Gettler, James J. McKenna,

 

Thomas W. McDade,

 

Sonny S. Agustin,

 

Christopher W. Kuzawa

Because cross-species evidence suggests that high testosterone (T) may interfere with paternal investment, the relationships between men's transition to parenting and changes in their T are of growing interest. Studies of human males suggest that fathers who provide childcare often have lower T than uninvolved fathers, but no studies to date have evaluated how nighttime sleep proximity between fathers and their offspring may affect T. Using data collected in 2005 and 2009 from a sample of men (n = 362; age 26.0 ± 0.3 years in 2009) residing in metropolitan Cebu, Philippines, we evaluated fathers' T based on whether they slept on the same surface as their children (same surface cosleepers), slept on a different surface but in the same room (roomsharers), or slept separately from their children (solitary sleepers). A large majority (92%) of fathers in this sample reported practicing same surface cosleeping. Compared to fathers who slept solitarily, same surface cosleeping fathers had significantly lower evening (PM) T and also showed a greater diurnal decline in T from waking to evening (both p<0 .05="" 4.5-year="" a="" among="" arrangements="" at="" baseline="" compared="" cosleepers="" decline="" did="" experienced="" fathers.="" fathers="" follow-up="" greater="" in="" longitudinal="" men="" not="" over="" p="" period="" pm="" predict="" same="" significantly="" sleeping="" solitary="" study="" t="" the="" these="" to="" were="" who="">0.2). These results are consistent with previous findings indicating that daytime father-child interaction contributes to lower T among fathers. Our findings specifically suggest that close sleep proximity between fathers and their offspring results in greater longitudinal decreases in T as men transition to fatherhood and lower PM T overall compared to solitary sleeping fathers.

Full article here