Background: The mothers of twins often suffer from sleeplessness. However, little is known about the relation of sleep behaviors between these mothers and their infants. The change of this relation with age has not been reported. The aims of this study are firstly to clarify the sleep behaviors of twin infants and their mothers by using actigraphy (four measurement periods at approximately 4- to 6-week intervals) and secondary to evaluate the relations of sleep behaviors between twin infants and their mothers.
Methods: Five twin pairs and their mothers (first-time mother) were participated in this prospective longitudinal study. Their sleep behaviors were recorded for 7 consecutive days by using an actigraph, when the infants reached a corrected age (CA) of 3-6 weeks, 8-11 weeks, 13-15 weeks, and 17-20 weeks. Sleep status was classified into 3 states: both infants sleeping, only one infant sleeping, and both infants awake.
Results: All infants were cobedded. The time awake during the nocturnal period decreased by almost 90 minutes from CA 3-6 weeks to CA 8-11 weeks. Sleep duration in the nocturnal period increased by almost 85 minutes, and the proportion of time with both infants sleeping rapidly increased in the same period. Maternal sleep duration during the period of both infants sleeping was positively correlated with CA.
Conclusion: This research revealed the transition of sleep behaviors in twin infants and their mothers in early infancy. Cobedding may facilitate more synchronized sleep states of twin infants.
Keywords: Actigraph; Longitudinal study; Primipara; Sleep development; Twin infants.