Closer sleeping proximity between fathers and children is associated with a greater decrease in the father's testosterone level, with possible implications for parenting behavior. The full report is published Sep. 5 in the open access journal PLOS ONE.
Fathers' testosterone levels have been associated with parenting behavior and involvement across species, with higher levels generally associated with lower parental involvement.
The authors of the current study, led by Lee Gettler of the University of Notre Dame, studied 362 fathers in the Philippines to determine whether their sleeping arrangements – either sleeping on the same surface as their children, in the same room, or separately – were related to their testosterone levels.
The researchers found that close sleep proximity between fathers and their children was associated with greater decreases in testosterone level as the men transitioned to fatherhood, as well as lower overall levels relative to fathers that slept apart from their children.
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Gettler LT, McKenna JJ, McDade TW, Agustin SS, Kuzawa CW (2012) Does Cosleeping Contribute to Lower Testosterone Levels in Fathers? Evidence from the Philippines. PLOS ONE 7(9): e41559. doi:10.1371/journal.pone.0041559