Active Fatherhood

A new study finds that dads who sleep near their children experience a drop in testosterone

As it turns out, mothers aren’t the only ones who are biologically adapted to respond to children. A new research study has found that fathers who sleep near their children experience a drop in testosterone, which helps them become a more focused and caring parent.

The study was conducted by anthropologist Lee Gettler from University of Notre Dame and was published recently in PLoS ONE. The research found that close sleep proximity between fathers and their children (on the same sleeping surface) results in lower testosterone than in fathers who sleep alone.

For the study, 362 fathers were sampled, all of whom were 25-26 years old. They were divided according to their reported nighttime sleeping location: solitary sleepers, those who slept in the same room as their children, and those fathers who slept on the same surface as their children. Saliva samples were collected upon waking and again just prior to sleep, and their testosterone levels were measured.

Though the waking hormone levels of the three groups showed no significant differences, fathers who slept on the same surface as their children showed the lowest evening testosterone. This hormone is known to enhance male mating effort, and higher levels have been linked to behaviours that might conflict with effective fathering, such as risk taking and sensation seeking.

According to Gettler, paternal physiology has the capacity to respond to children. ‘Our prior research has shown that when men become fathers, their testosterone decreases, sometimes dramatically, and that those who spend the most time in hands-on care—playing with their children, feeding them or reading to them—had lower testosterone. These new results complement the original research by taking it one step further, showing that nighttime closeness or proximity between fathers and their kids has effects on men’s biology, and it appears to be independent of what they are doing during the day,’ Gettler writes.

He adds that there is growing evidence that men’s physiology can respond to involved parenthood—something that was thought to be limited to women. ‘This suggests to us that active fatherhood has a deep history in the human species and our ancestors… We see increasing biological evidence suggesting that males have long embraced this role.’

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