SYNCHRONIZING CIRCADIAN-RHYTHMS IN EARLY INFANCY

Entrainment to the 24-hour light-dark cycle is of adaptive significanc e to mammals. Human infants are no exception, but some postnatal care habits prevalent in developed countries can interfere with the physiol ogical mechanisms underlying circadian synchronization. We describe th e physiological mechanisms of entrainment to the light-dark cycle in f etuses and newborns, and some common parental care behaviors which sub ject the developing circadian system of the newborn to conflicting tem poral cues. Improvements in parental care are proposed which may impro ve the circadian synchronization of newborns, and their parents or car egivers.