New mums are being urged to be cautious about returning to work too quickly, after a QUT study found one in two were still excessively sleepy four months after giving birth.
Dr Ashleigh Filtness, from QUT's Centre for Accident Research & Road Safety - Queensland (CARRS-Q), studied the sleep patterns and tiredness of postpartum mums and found despite new mums recording stable night sleep times at 18 weeks, they continued to report being excessively tired.
The CARRS-Q study, published in PLOS ONE, followed 33 healthy new mums who recorded their postpartum sleep patterns in 15 minute increments during weeks 6, 12 and 18.
"Sleep disruption strongly influences daytime function, with sleepiness recognised as a risk-factor for people performing critical and dangerous tasks," she said.
Dr Filtness said the study had significant implications for decisions-makers about when women should return to work, with current government paid parental leave entitlements ceasing at 18 weeks.
"This brings into question whether four months parental leave is sufficient to ensure daytime sleepiness has diminished to a manageable level before returning to work," she said.
"It is important when developing regulations for parental leave entitlements that policy makers take into account the high prevalence of excessive daytime sleepiness experienced by new mothers.
"With the birth of every baby the new mother must adjust to the demands of parenting and one aspect of that is to remain functional while experiencing potentially severe sleep disruption.
"To put this into context, the assessment tool used to determine new mums' sleepiness is also used by GPs to determine clinically relevant levels of sleepiness.
"If any other otherwise healthy person presented to a doctor with this degree of sleepiness they would likely have been offered advice regarding implications for daytime impairment including the impact on sustaining attention and decision making."
Dr Filtness said the study also found while new mums were still waking on average twice a night to attend to their babies at 6, 12 and 18 weeks - their total sleep time was about 7 hours and 20 minutes.
She said Australian new mothers actually slept more than the average American worker (6h 53mins).
"So while postpartum women experienced disturbed sleep, they didn't necessarily experience total reduced sleep time," she said.
"What we found was that inevitably, new mothers will wake in the night to attend to their infant and the number of times they wake remains consistent during the first 18 postpartum weeks.
"Sleep disruption reduced over time and it appears this was driven by a reduction in the time it took for new mums to return to sleep, suggesting improved efficiency by mothers at settling their infant or the development of the infant's circadian rhythm.
"These findings highlight the importance of sleep quality as opposed to sleep quantity, especially during the first 12 weeks."
"Soon-to-be mums should be aware of the importance of their own sleep and consider how they are going to preserve their own sleep during the first few months of caring for a baby," she said.