ABSTRACT
Infant sleep is hugely variable in terms of 24-hour duration, and changes over time. Studies of infant sleep began in earnest in the 1950s: infant sleep characteristics were ‘defined’ based on studies of formula-fed babies sleeping alone, and sleep was ‘measured’ via maternal reports of whether she was aware that the baby woke in the night. The vast majority of breastfeeding mothers tend to sleep with their babies in their bed as a strategy to cope with sleep disruption for at least some of the time. The relationship between night-time breastfeeding, frequent feeding and bed-sharing of course raises concerns about infant sleep safety and sudden infant death syndrome. As mammals, the defining characteristic of our taxonomic class is producing milk for our babies, but as a species humans also have other unique defining characteristics: bipedalism and unusually large brains.
