NEW mothers who get less than six hours' sleep a night face an increased risk of postnatal depression.

Strong links between sleep deprivation and depressive symptoms in new mothers were found in a review of more than 100 international studies.

A lack of sleep could make them feel sad, tired and unable to concentrate, Australian researcher Kerry Thomas told the Australian Psychological Society’s annual conference in Canberra yesterday.

"Women whose babies wake several times during the night have a greater risk of developing depression, and that’s both at four weeks postpartum and eight weeks postpartum stage," she said.

"Women who receive less than six hours of sleep a night in a 24-hour period also have an increased risk of developing depression."

About 16 per cent of Australian women are believed to develop postnatal depression, also known as the "baby blues", after giving birth.

Ms Thomas, a research student at the University of Canberra, said there was growing evidence that sleep problems were related to the development of depression generally.

Ms Thomas said for many women sleep problems could begin in pregnancy and last for several months after the birth.

She said community-based residential units were often effective in relieving symptoms of depression by helping new mothers find ways to settle their babies.

"It’s not a cure (for their depression), but the mum does start to feel better," Ms Thomas said.

"when you have children in the home it’s not just a matter of getting more sleep, it’s a strategy.

"you have to negotiate sleep and plan for sleep, which you didn’t have to do before you had children," she said.

Ms Thomas plans to follow up her research by recruiting 60 new mothers next year to study their sleep patterns for up to a year after their babies are born.

The researcher will examine their stages of sleep and monitor any symptoms of depression.