OBJECTIVES: To explore the association between maternal distress and depression in the first years of a newborn's life and the child's sleeping behaviour and problems associated with this behaviour. To asses the effectiveness of an outpatient-based individualised behaviour modification programme to modify children's sleep behaviour and to decrease levels of maternal distress and depression. METHOD: Families were referred to an outpatient childhood sleep problems clinic. Intervention consisted of an individualised management programme including recognised modes of child sleep behaviour management ('controlled crying', 'cold turkey,' rewards) together with occasional use of short-term (less than 2 weeks) tapering dose sedating medication for the child. Two months after the initial contact with the clinic, families completed a second questionnaire collating similar data to that collected at time of enrolment. RESULTS: A total of 114 consecutive families referred to the clinic provided initial data. Follow-up questionnaires were returned by 70 (61%). Significant change was recorded in children's sleep parameters including reduction in mean number of night time awakenings (4.1-1.3, P < 0.001), proportion of children requiring longer than 30 min to settle at night (49% to 21%, P < 0.01) and in the proportion of children settling after 8 pm (51% to 33%, P < 0.01). Sleep problem rating on a 0-10 scale decreased from a mean of 8.1-3.1 (P < 0.001). On initial assessment, 40% of mothers had Edinburgh Postnatal Depression Scale (EPNDS) scores greater than 12 (screening cut-off point). At repeat assessment, 4.3% had scores greater than 12. The mean score on the EPNDS fell from 11.2 to 5.8 (P < 0.001). CONCLUSIONS: An outpatient-based individualised approach to modifying children's problematic sleep behaviour using recognised behaviour management techniques is effective. Modification of problematic childhood sleep behaviour is associated with significant improvement in maternal mood. Given the high incidence of childhood sleep problem and diagnosed postnatal depression, it is likely significant numbers of mothers being diagnosed as having postnatal depression are suffering the effects of chronic sleep deprivation. Management of postnatal mood disorder and childhood sleep behaviour must occur with due recognition to their close association.