“We know from biological, medical research that interrupted sleep is clearly not restful, it’s poor quality sleep. It doesn’t have the restorative benefits that we need to help support the top functioning in other realms,” says study researcher Sarah Burgard, PhD, an associate professor of epidemiology and sociology at the University of Michigan School of Public Health in Ann Arbor.
Women in their 20s and 30s, the prime childbearing years, appeared to be most affected by this sleep disparity between the sexes, a time when many women are trying to advance in their professions.
“The time when many women are having their children is actually a very important career building period, right?” Burgard asks.
“So let’s say you have primary responsibility for getting up with the kids at night and you’re doing it for several years if you have more than one child. That’s coming at a time when you need to be ‘on’ at work all day. That’s when the promotions are happening, when some really important salary building stuff is happening. That’s going to affect your salary trajectory for the rest of your life,” she says.
Understanding Why Women Are More Likely to Get Up at Night
So what’s to explain why women are more likely to be the nighttime caregivers in their households than men?
Part of the explanation may be biological. Women who are breastfeeding, for example, may be the only ones who can feed children in the middle of the night.
And a 2007 brain imaging study found that people reacted differently to a child’s cries depending on their sex and whether or not they were parents, leading scientists to wonder if men just don’t hear nighttime cries as quickly as women do.
And Burgard thinks some children may learn to prefer their mother’s attention at night, and in that way, make the choice for weary parents.
Some women may also take particular pride in claiming the role of primary caregivers in their homes, exhausting as that may be.