For three-year-old children whose mothers visited a health center in Tokyo for consultation about childrearing problems in 1976 and 1996, their co-sleeping with adult and the related fac tors were examined. The major results were as follows.1. In 1996, the proportion of mothers who co-sleep with toddlers is high among those with jobs, and the mothers who experienced co-sleeping in their own childhood and whose child has evolopmental risk tend to co-sleep.2. Sleeping arrangements, including co-sleeping, of children with developmental risks differ in quality from that of handicapped children.3. Mother's co-sleeping behavior is interrelated with her intention of childcare, information source of childrearing, consultants in neighborhood and the matter of her major interest. From these results, it is suggested that sleeping arrangements of children is associated with factors concerning both mothers and children and it is recognized as an indicator of assessing mother's nurturing behavior and child's developmental risks.
