Sleepless nights could plunge new mothers into depression, researchers have found.
Studies showed that the risk of post-natal depression was higher for new mothers who slept for fewer than six hours some nights than for others who regularly slept longer, the Australian Psychological Society's annual conference has been told.
The findings were presented in a review of international research by University of Canberra research student Kerry Thomas.
She said while changes to sleep patterns were an expected part of any new mother's life, many underestimated the potential detrimental effects on their emotional health.
These could emerge in the months after delivery and persist for several years.
Ms Thomas said the evidence available showed a strong link between sleep deprivation and the development of depressive symptoms in new mothers.
"The link between insomnia and depression in the general population has been well documented, but sleep deprivation is rarely studied as a risk factor for postnatal depression," she said.
"The few studies that have been carried out show an undeniable link."
Ms Thomas said during pregnancy and in the early weeks after birth the sleep of new mothers was significantly altered, with lower sleep quality, less total sleep time and more disrupted sleep.
If this altered sleep pattern persisted for several months after delivery, some women may develop depressive symptoms.
Symptoms of sleep deprivation include fatigue, concentration problems, reduced ability to function in the daytime and poorer quality of life, sleepiness and lethargy.
A person not getting sufficient sleep can also experience negative moods, such as sadness and feelings of being unable to cope.
Ms Thomas said research indicated that improving the sleep patterns of both infants and their mothers in some cases led to a reduction in maternal depression symptoms for mothers.
In one 2008 study more than half of the mothers suffering postnatal depression saw a significant improvement in symptoms with increased sleep, and the benefits were still evident four months later.
Ms Thomas said there were a number of programmes that had helped parents reduce night-time waking.
These were largely provided through residential sleep units and maternal and child health centres, but online programs had also resulted in babies falling asleep sooner and waking less often in the night, with improvements to their mothers' mood reported two weeks later.
"Many new mothers underestimate the effect of disrupted sleep on their emotional health and would benefit from guidance on the impact of sleep deprivation, strategies for gaining more sleep in the postnatal period and early training in sleep strategies for themselves and their infants," Ms Thomas said.
"Within many maternal health settings, women are regularly screened for depression and other physical and emotional problems, and their babies are assessed.
"These settings would be ideal for providing information to women who are having trouble getting enough sleep due to their baby's sleep patterns, for running short group workshops demonstrating techniques and for providing ongoing support."