The overall aim of this study is to describe sleep patterns in infants as they transition from home to child care, including 24-hour sleep duration, changes in the timing of daytime naps, and changes in nocturnal sleep periods; to describe potential sleep disrupters, such as temperature, light and noise, in home and child care settings that may impact sleep quality and sleep patterns; to describe markers of parent and infant stress levels during the transition to child care; to describe markers of infant circadian rhythm during the transition to child care.