Washington, July 1 : A new study has established a direct link between poor sleep and depression in women after giving birth.

Reported in the journal SLEEP, the study suggests that postpartum depression may aggravate an already impaired sleep quality, as experiencing difficulties with sleep is a symptom of depression.

A research article reveals that 21 percent of depressed postpartum women included in the study reported that they were also depressed during pregnancy, and that 46 percent reported at least one previous depressive episode prior to conception, suggesting that new mothers diagnosed with postpartum depression are not merely reporting symptoms of chronic sleep deprivation.

Experts behind the study say that their findings suggested that two months after delivery, poor sleep was associated with depression when adjusted for other significant risk factors, such as poor partner relationship, previous depression, depression during pregnancy and stressful life events.

Sleep disturbances and subjective sleep quality were the aspects of sleep most strongly associated with depression. Overall, nearly 60 percent of the postpartum women experienced poor global sleep quality, and 16.5 percent had depressive symptoms.

Lead author Dr. Karen Dorheim, psychiatrist at Stavanger University Hospital in Norway, points out that depression after delivery is often not identified by new mothers, whereas tiredness and lack of sleep are common complaints.

The researcher says that these symptoms may be attributed to poor sleep, but the tiredness could also be caused by depression.

"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. 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," said Dorhei.

For their study, the researchers collected data from 2,830 women who gave birth to a live child at Stavanger University Hospital in Norway between October 2005 and September 2006.

Their study suggested that depression, previous sleep problems, being a first time mother, not exclusively breastfeeding or having a younger or male infant were factors associated with poor postpartum sleep quality. It also showed that better maternal sleep was associated with the baby sleeping in a different room.

According to authors, the first three months after delivery are characterized by continually changing sleep parameters, and women who are tired during this period may attribute this to poor sleep, but the tiredness could alternatively be caused by depression; thus talking about sleep problems may provide an entry point for also discussing the woman''s overall well-being.

Individual women may react differently to shorter sleep duration and lower sleep efficiency during the postpartum period, and that 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. (ANI)