In the third trimester of her pregnancy, Melissa Nevarez-Brewster wasn’t sleeping well.
“I woke up every hour or hour and a half just to go to the bathroom,” the first-time mom says. “And then, in the later weeks, just moving an inch would wake me up because of how uncomfortable I was.”
Nevarez-Brewster says she’s actually getting better sleep now that her baby is born, despite those infamous middle-of-the-night feedings.
“Now, I can offset a little bit with my partner,” she says. “I don’t have to do all of the feedings, so I get longer periods of sleep.”
Nevarez-Brewster hasn’t just experienced the effects of disrupted sleep during pregnancy—she also studies it. The fifth-year PhD student at the University of Denver has been interested in psychology and human development since her undergraduate days at the University of Utah.
When she came to DU in 2020, she began working with her now-advisor, psychology professor Elysia Davis, in the developmental psychology program. Davis’ research focuses on how prenatal experiences and risk factors influence how babies develop, both emotionally and physically. One of Davis’ recent studies, for example, suggested that treating depression during pregnancy can lead to longer gestation time and healthier babies.
Davis’ work fascinated Nevarez-Brewster, but she wanted to dig deeper. She remembered a book she read in undergrad on human development and the risk factors for premature babies.
“I was a premature baby, and it kind of got me thinking about how we don’t know a lot about pregnancy and all the processes that affect the baby,” she says. “We tend to think of the baby’s development as starting from birth, but there’s so much that happens before that.”
Digging into the science of sleep
When Davis asked Brewster what she wanted to study, she chose sleep—years before experiencing her own pregnancy-related sleep challenges. As luck would have it, Davis already had data on sleep during pregnancy, self-reported by moms in her previous studies.
They used the data to track the trajectories of sleep quality of different pregnant individuals in the samples. They quickly realized that there was a gap in the published literature on sleep during pregnancy, especially when it came to how sleep during pregnancy affected babies after birth. So, Nevarez-Brewster conducted a systematic review of 34 different papers that looked at sleep during pregnancy.
“Most of the outcomes out there that are related to poor sleep tend to focus on prematurity or low birth weight or birth length, but there weren’t any systematic reviews that looked at just the outcomes after birth,” she says.
Using the gaps Nevarez-Brewster found, Davis and associate professor of psychology Jenalee Doom applied for a grant from the National Institutes of Health (NIH) to study the effects of prenatal sleep on children’s cardiovascular health after birth.
While Nevarez-Brewster isn’t part of this particular study—she’s on maternity leave—Davis and Doom were inspired in part by Nevarez-Brewster’s existing work on sleep during pregnancy. The two researchers wanted to take a different approach than that of previous studies, which tended to rely on moms’ self-reporting of their sleep quality.
“While that is very important, we also wanted to know how many times moms are waking up at night or if they’re having a hard time falling asleep. These are all things that we can measure with activity monitors,” says Doom. “So, we’re able to ask moms how they slept, but we’re also looking at those objective metrics of sleep quality as well, which hasn’t been done as much in previous studies.”
The researchers will recruit people early on in pregnancy and ask them to self-report on their sleep quality and wear sleep activity monitors—Fitbit-like devices—at the beginning, middle, and end of their pregnancies.
“We’ll also follow both mom and baby until eight months postpartum,” Doom says. “Our final assessment of the study will have both moms and babies wearing sleep monitors at the eight-month postnatal visit to examine both mom and baby’s sleep quality.”
Looking beyond the data
Nevarez-Brewster says it’s important to study how sleep during pregnancy—both good and bad— affects children, simply because it hasn’t really been done before.
“Are there beneficial outcomes to improving sleep during pregnancy? We don’t really know that,” she says.
And when it comes to who gets good sleep, Nevarez-Brewster says, it’s not black- and white.
“Like everything else, there are systemic differences in who gets better or worse sleep,” she says. “One of the things that I like to bring up is people who live in subsidized housing—they don’t control the temperature in their households, and that affects how they sleep, which has a trickle-down effect.”
Nevarez-Brewster wanted to quantify the poor sleep she felt she was getting during pregnancy, so she took home a sleep monitor from Davis’ lab—and discovered how often she was waking up.
But now that she’s postpartum, Nevarez-Brewster is sleeping better and, after her parental leave, she’s eager to return to her research on sleep during pregnancy with Davis and Doom. Eventually, she hopes she might even sleep through the night.