Techniques for noninvasively acquiring the vital information of infants and young children are considered very useful in the fields of healthcare and medical care. An unobstructive measurement method for sleeping infants and young children under the age of 6 years using a sheet-type vital sensor with a polyvinylidene fluoride (PVDF) pressure-sensitive layer is demonstrated. The signal filter conditions to obtain the ballistocardiogram (BCG) and phonocardiogram (PCG) are discussed from the waveform data of infants and young children. The difference in signal processing conditions was caused by the physique of the infants and young children. The peak-to-peak interval (PPI) extracted from the BCG or PCG during sleep showed an extremely high correlation with the R-to-R interval (RRI) extracted from the electrocardiogram (ECG). The vital changes until awakening in infants monitored using a sheet sensor were also investigated. In infants under one year of age that awakened spontaneously, the distinctive vital changes during awakening were observed. Understanding the changes in the heartbeat and respiration signs of infants and young children during sleep is essential for improving the accuracy of abnormality detection by unobstructive sensors.

This longitudinal study examined relations between family expressiveness and child behavior problems. I explored how maternal depressive symptoms and sensitivity might mediate associations between family expressiveness and child behavior problems. Mothers completed the Family Expressiveness Questionnaire at 9 months, the Beck Depression Inventory at 18 months, and the Child Behavior Checklist at 30 months. Maternal sensitivity during mother-child interactions was assessed at 18 months. A path analysis revealed that maternal depressive symptoms but not maternal sensitivity mediated the effect of family expressiveness on child behavior problems, although family expressiveness was not directly related to child behavior problems. These results suggest that the family emotional climate indirectly plays a role in the child psychological functioning.