||The purpose of this study was to investigate the characteristics of sleep-wake behavior during the period from late pregnancy to puerperium by evaluating the number of actigraphic activities in a prim...ipara woman and to compare the results with the findings from sleep logs. An regularity of the sleep-wake behavior was not possible during about 5th weeks after delivery. When compared to that in the 37 to 39 weeks of pregnancy, the wake after sleep onset (WASO) was longer during the entire postpartum period. During the second and third weeks of postpartum period, the sleep efficiency was lowest, and the WASO was longest, but they both began to recover slightly after that. Most waking hours at night were spent on breast-feeding or taking care of baby. Except for the number of daytime naps and sleep latency, the results of actigraph strongly correlated with the contents of the sleep logs. These results were indicative of the association between the lactation cycle to neonate and the sleep-wake cycle.