When babies start day care, they experience many changes, some of which may affect their risk for sudden infant death syndrome (SIDS). The investigators want to find out if stress or change in the baby's sleep patterns can be a reason for this increased risk for SIDS.

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.

Inclusion Criteria:

• Infants who are less than 3 months of age from English-speaking families where one or both parents live in the household will be eligible to participate. If the infant will be entering child care, the infant must be entering a licensed child care center, and child care entry must be between 60 and 120 days of age.

Exclusion Criteria:

• S/he was born prematurely, with a gestational age less than 37 weeks at birth, or had a birth weight <2500 grams (5-1/2 lbs)
• S/he has any medical problems that require ongoing care by a subspecialty physician

infants from 0 to 3 months in the United States