Relationship Between Infant and Mother Circadian Rest-Activity Rhythm Pre- and Postpartum, in Comparison to an Infant With Free-Running Rhythm

Abstract

Some infants show a free-running rhythm in their rest-activity. We do not know why, nor do we know exactly what the entrainment factors are for the development of the normal 24-h rest-activity rhythm. Actigraphic recordings on 10 primiparae during late pregnancy and these mothers and their infants during the 2nd, 6th, and 12th wks after birth were made over 3–5 continuous days to investigate maternal and infant entrainment. One infant showed a free-running rest-activity circadian rhythm. In late pregnancy, the period in the autocorrelogram of the mother with the free-running infant was longer than the significant period of the mean autocorrelogram of the mothers with non-free-running infants. The finding of this study indicates the free-running rhythm of infant is not reset by maternal entrainment factors. (Author correspondence: [email protected])

Keywords:

• Circadian rhythm
• Entrainment of rhythms
• Free-running
• Infant
• Mother
• Rest-activity

ACKNOWLEDGMENTS

We thank Dr. Makoto Honda of the Tokyo Metropolitan Institute of Medical Science, who supported this study. We appreciate the cooperation of the women who participated in our investigation. This study was supported in part by a Grant-in-Aid for Scientific Research (C17605013), provided by the Japan Society for the Promotion of Science.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.