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

Abstract

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). Among men who were not fathers at baseline (2005), fathers who were cosleepers at follow-up (2009) experienced a significantly greater longitudinal decline in PM T over the 4.5-year study period (p<0.01) compared to solitary sleeping fathers. Among these same men, baseline T did not predict fathers' sleeping arrangements at follow-up (p>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.

The Effects of Long Term Sleep and Exercise Deprivation on Total Serum Testosterone in Male Professional Drivers

“…Such study is an agreement with our findings (Monico et al, 2013;Maggio et al, 2013;Jauch et al, 2013;Gettler, 2012).…”

“…Those fathers who sleep with their children at night and provide care to their children have low morning testosterone level as compared to those fathers who do not sleep at night with their children and do not provide care. This difference in morning testosterone occurs because the co-sleeper fathers have a disturbed sleep because of their children (Gettler, 2012). The drivers were also exposed to marijuana and cigarette smoke.…”

Theoretical frameworks for human behavioral endocrinology

“…Muller et al (2009), for instance, showed that testosterone did not differ between fathers and non-fathers among the pastoralist Datoga in which men had little direct involvement with child-care, but that fathers had lower testosterone than non-fathers among the Hadza, for whom frequent contact with children (including co-sleeping) was the norm. Other studies have likewise shown that variables like co-sleeping with children (Gettler et al, 2012) and ratings of overall paternal investment (Alvergne et al, 2009) negatively predict testosterone concentrations among fathers.…”

The impact of parenthood on physical aggression: Evidence from criminal data

“…Studies of male testosterone including both married and unmarried fathers are, however, rare; Gray et al (2006) found that resident-fathers had non-significantly higher T levels than 'visiting', non-resident, fathers in Jamaica, although this may in part reflect self-selecting participants who were willing and able to bring their child and the child's mother to the hospital for testing. Contrastingly, other data suggest that cosleeping with offspring can significantly reduce testosterone, suggesting that while pair-bonding itself may not be a necessary precondition for an effect of parenthood on testosterone, close interaction and activities likely to induce increases in oxytocin and prolactin may be (Gettler et al, 2012). Indeed a number of studies have suggested that interactions with infants may affect testosterone in contexts other than parenting (van Anders et al, 2014).…”