It is important to ask a new mother suffering from tiredness about how poor sleep affects her daytime functioning and whether there are other factors in her life that may contribute to her lack of energy, said lead author Signe Karen Dørheim, MD, PhD, a psychiatrist at Stavanger University Hospital in Stavanger, Norway. There are also helpful depression screening questionnaires that can be completed during a consultation. Doctors and other health workers should provide an opportunity for postpartum women to discuss difficult feelings.

The study objective was to assess the prevalence of and risk factors for concurrent postpartum maternal sleep problems and depressive symptoms, to identify factors independently associated with either condition, and to examine associations between specific components of postpartum sleep and depression.

A total of 4191 women delivered at Stavanger University Hospital from October 2005 to September 2006 had a questionnaire 7 weeks after delivery, with a response rate of 68% (n = 2830). Mean maternal age at the time of reply was 30 years.

Sleep characteristics were evaluated by the Pittsburgh Sleep Quality Index (PSQI), with sleep problems defined as a PSQI score of more than 5. Depressive symptoms were evaluated by the Edinburgh Postnatal Depression Scale (EPDS) with depression defined as an EPDS score of 10 or higher.

The occurrence of sleep problems was 57.7%, and of depression was 16.5%. Self-reported mean nightly sleep efficiency was 73% and sleep duration was 6.5 hours.

Poor postpartum sleep quality occurred due to depression, history of sleep problems, primiparity, not exclusively breast-feeding, or having a younger or male infant. After adjustment for other known risk factors for depression like poor partner relationship, history of depression, depression during pregnancy, and stressful life events, poor sleep remained associated with depression. The aspects of sleep most strongly linked to depression were sleep disturbances and subjective sleep quality.

Poor sleep was associated with depression independently of other risk factors, the study authors write. Poor sleep may increase the risk of depression in some women, but as previously known risk factors were also associated, mothers diagnosed with postpartum depression are not merely reporting symptoms of chronic sleep deprivation.

The study limitation included cross-sectional design precluding determination of causality and reliance on self-reported symptoms.

The sleep of women with a history of depression may be more sensitive to the psychobiological (hormonal, immunological, psychological, and social) changes associated with childbirth, the study authors conclude. Sleep could act as a moderator between these risk factors for depression and the precipitation of depression in women vulnerable to such sleep changes during the postpartum period. Longitudinal studies are needed to evaluate whether treatment of maternal sleep problems reduces depression and whether treatment of maternal depression improves sleep quality.