Methods Inf Med 2018; 57(03): 152-157
DOI: 10.3414/ME18-02-0001
Focus Theme – Original Article
Schattauer GmbH

Application of Empirical Mode Decomposition to Mother and Infant Physical Activity

Synchronization of Circadian Rhythms is Associated with Maternal Mental Health
Etsuko Shimizu
Graduate School of Education, The University of Tokyo, Tokyo, Japan
Toru Nakamura
Graduate School of Engineering Science, Osaka University, Osaka, Japan
Jinhyuk Kim
Department of Biobehavioral Health, The Pennsylvania State University, PA, USA
Kazuhiro Yoshiuchi
Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
Yoshiharu Yamamoto
Graduate School of Education, The University of Tokyo, Tokyo, Japan
› Author Affiliations
This work was partly supported by Grants-in-Aid for Exploratory Research [15K12679] (to T. N.) from the Ministry of Education, Culture, Sports, Science and Technology. This study was also supported by funds for SEEDS research project from the Center for Early Childhood Development, Education, and Policy Research, the University of Tokyo (to Y. Y.).
Further Information

Publication History

received: 19 January 2018

accepted: 11 February 2018

Publication Date:
02 May 2018 (online)


Background: The mutual dependencies between mother and infant circadian rhythms are important for examining disturbances of maternal circadian rhythms, which are considered substantial risk factors for the development of maternal depression during childrearing periods.

Objectives: We characterized the mutual dependencies of maternal–infant circadian rhythms by an index of synchronization properties and then tested the hypothesis that such an index, specifically the instantaneous phase differences between their rhythms, is associated with maternal mental health.

Methods: We performed longitudinal recordings of maternal symptoms of fatigue, stress, and mood states by ecological momentary assessment, together with simultaneous measurements of mother and infant physical activity data in daily life, on 20 mother–infant pairs for a period of >1 week. The circadian components in their physical activity data were extracted by ensembled bivariate empirical mode decomposition, and the corresponding instantaneous phases were then obtained based on the Hilbert transformation. The associations between diurnal maternal symptoms and absolute phase differences between mother and infant circadian rhythms were tested by multilevel models.

Results: Diurnal fatigue and depressive mood scores showed positive and significant correlations (p < 0.05) with the increase in instantaneous mother–infant phase differences, indicating the significant role of synchronization of mother–infant circadian rhythms for maintaining maternal mental health.

Conclusions: These findings suggest that modifications of maternal and/or infant circadian rhythms may lead to the improvement of maternal mental health during child-rearing periods.