Beyond practices and values: toward a physio-bioecological analysis of sleeping arrangements in early infancy

Should my baby sleep in my bed? There are clear reasons to do so, such as for warmth, comfort, bonding, and cultural tradition, but there are also clear reasons against doing so, such as increased risk of sudden infant death syndrome (Moon, 2011). Besides being a recurring practical question for parents, co-sleeping is a perennial academic issue as well. Hence, Shimizu et al.'s (2014) aim to examine “parenting practices and underlying cultural values of Japanese mothers” (p. 8) related to sleeping arrangements is timely and valuable. The authors predicted that mother-infant co-sleeping would decline from the 1960–1980s to 2008–2009 due to modern parents adhering to values that are more adaptive in an educated, urban, technologically and economically advanced society that has higher female participation in the workforce. However, they found equal prevalences for co-sleeping in Japan in the 1980s as compared to now. The authors suggested that this historical continuity is due to societal expectations which are in conflict with mothers' desire for gender egalitarianism. Here, we offer a complementary set of explanations as to why co-sleeping might be preserved among Japanese mothers over five decades of enormous social change, and we propose a direction where future studies on parent-child sleeping arrangements should go.