A Cluster Analysis of Reported Sleeping Patterns of 9-Month Old Infants and the Association with Maternal Health: Results from a Population Based Cohort Study.

The aim of this study was to identify, using cluster analysis, novel sleep phenotypes in a population based cohort of infants, and to explore the associations between infant sleep profiles and their mothers' health and well-being. 11,134 mothers of 9-month old infants were interviewed as part of the Growing Up in Ireland National Longitudinal study and reported on their health and infant's sleep patterns. 16 infant sleep variables were recorded together with measures of parental stress, depression, health and well-being. Multiple iterations of a two-step hierarchical cluster analysis were carried out to identify the optimum number of clusters and the subset of parental-reported sleep variables required to identify distinct sleep profiles. Four distinct sleep profiles were identified based on the following variables; (1) infant sleep duration at night, (2) parental sleep duration, (3) does baby wake during night (yes, no)? (4) Usual sleep location for most of the night and, (5) parental reporting of problem infant sleep patterns. This identified two less favorable profiles with both infants and mothers sleeping less and where mothers are more likely to report their infants' sleep patterns as problematic. Mothers of infants belonging to these sleep profiles were more likely to have higher levels of stress, depressive symptoms, and poorer self-reported health than other sleep profiles. Breastfeeding was associated with both groups and rates were highest in a group of infants that were more likely to co-sleep with their parents and have diverse ethnic backgrounds. This study demonstrates, for the first time, two infant sleep profiles with distinct phenotypical frameworks that are significantly associated with maternal stress, depression, and poorer self-report of health.