This prospective study of 63 women was designed to investigate the relationship between sleep disruption prior to the birth, during labour and in the early postpartum period and the subsequent development of the postnatal blues. The results from this preliminary study suggest that two factors: (a) a night-time labour; and (b) a history of sleep disruption in the latter stages of pregnancy, may have aetiological importance in the development of postnatal blues. There was little evidence from this study to suggest that sleep disruption on the nights following the birth, the third sleep factor investigated, had any impact on the expression of the blues.