Changes in sleep-wake cycle during the period from late pregnancy to puerperium identified through the wrist actigraph and sleep logs.

The purpose of this study was to understand the sleep-wake cycle during the period from late pregnancy to about 3 months of postpartum by evaluating the number of actigraphic activities in four women (one multipara and three primi gravidae), and to compare the results with the findings from sleep logs. An irregularity of the sleep-wake cycle with increased number of wakings at night was notable during about 1 month after delivery, compared to the late pregnancy period, and subsequently this number tended to decrease. These results were indicative of the association between the lactation cycle to neonates and the sleep-wake cycle.