If you’re always constantly getting the 3pm yawns, it might have something to do with those small humans you’re raising – and the way they meddle with your sleeping patterns.
A new study by the University of Queensland has confirmed that mums, on average, sleep significantly less than non-parents and dads alike.
“The presence of young children in the household is associated with reduced sleep, and more so for women than men,” researcher Stefanie Plage, from UQ's School of Social Science, said.
The figures show that men and women without kids sleep 50 hours a week on average, compared with 48.6 hours for parents of one child and 46.2 hours a week for those with three children.
But parents don't share that sleep deprivation equally. While men with three kids sleep 48.2 hours a week, mothers of three get just 44.5 hours a week.
(If you're already a mother, this news may come as no surprise. If you're not... well, relish your Sunday morning sleep-ins now, because you won't see so many of them once you have a child whose idea of a good time is waking up with the sunrise.)
The parents of – you guessed it – very young children suffer the most when it comes to sleep deprivation.
"Having babies of less than one year of age reduces parental sleep (especially maternal sleep) the most," Plage said.
The finding that parents of very young children lose out on sleep most significantly echoes that of a 2013 UK study, which found that parents of newborns lose more than six weeks' worth of sleep in a single year.
According to the research, by ErgoFlex, UK parents get just 5.1 hours of sleep per night in the first year of their child's life.
That sleep loss equates to a sleep loss of 20.3 hours per week, equivalent to a whopping 44 days over the course of a year.
Fortunately as the kids get older, parents may have a chance to catch up on that sleep debt: By the time the youngest child reaches the age of four, mums and dads get 49.7 and 48.4 hours’ sleep a week respectively, the study found.
That's almost – almost – as much as people with no kids at all.
Excuse us while we calculate exactly how many days until that glorious fourth birthday...
What funny 'mum fails' have you made while sleep deprived? Watch mothers reveal their own below...