The science of healthy baby sleep

"Prior to the 19th Century, infant sleep was not generally a concern of new parents, with popular parenting manuals of the time failing to mention anything about it," anthropologists Jennifer G Rosier and Tracy Cassels write. "When an infant woke, there was either an awake family member ready to care for the infant or a sleeping family member next to the baby who was able to quickly respond. There was also an understanding that babies (and adults) slept when they needed to sleep and that they were awake when they needed to be awake."