Maternal Sleep May Have a Role in Passing Stress Between Generations

In the nine months that a baby develops and grows inside its mother’s womb, it may not be able to see the outside world, but it is acutely sensitive to its mother’s environment. Through the hormones, immune molecules, and nutrients that course through her veins, a mother can signal a variety of types of stress to her unborn child, in some cases impacting development.

Scientists have only a partial understanding of how parental stress during pregnancy might shape their child’s health. Recent research from Columbia’s Claudia Lugo-Candelas, suggests that poor sleep may have an important role: Her study found that mothers who don't get enough quality sleep during pregnancy are more likely to have children with neurodevelopmental issues like attention-deficit/hyperactivity disorder (ADHD).

This year, Lugo-Candelas was named a Herbert and Florence Irving Scholar and awarded $225,000 to continue her research into this link. She plans to use the funds to explore the hormones and other molecules that connect maternal sleep, stress during pregnancy, and children’s neurodevelopment.

Lugo-Candelas, who is the Florence Irving Assistant Professor of Medical Psychology in the Department of Psychiatry at the Vagelos College of Physicians and Surgeons, says that if researchers and clinicians are more aware of the importance of maximizing quality sleep, or minimizing stress, during pregnancy, they can develop better ways to promote these behaviors and shape children’s health risks. It’s also an issue, she says, that has broad implications for health equity: Minoritized populations in the U.S. are often exposed to more stress and also have higher rates of pregnancy complications.

“Instead of looking at sleep and stress as something else to worry about during pregnancy, I like to think of it is as an additional opportunity to intervene that we didn’t know we had,” Lugo-Candelas says.

The roots of self-regulation

When Lugo-Candelas was growing up in Puerto Rico, her mother directed a special education school. Lugo-Candelas remembers seeing the behavioral and emotional challenges that many of the children at the school faced, and learning how psychologists at the school helped them cope. She knew early on that it was a field she wanted to work in.

In college at the University of Puerto Rico, she got her first taste of research, working in a lab that studied how prenatal cocaine exposure impacted young children’s self-regulation—their ability to manage their emotions and behaviors.

Later while pursuing her graduate degree in clinical psychology at the University of Massachusetts, Amherst, Lugo-Candelas used electroencephalogram (EEG) tests to measure the brain activity of children with ADHD. Her research showed that when normal children were faced with a frustrating task, they put more attention toward completing it. But when children with ADHD faced the same task, their attention quickly waned. The more frustrated they became—and the more they were asked to regulate that frustration—the less attention they paid to solving the task.

Lugo-Candelas was interested in better understanding the roots of self-regulation; why did some children struggle with it so much? She began a postdoctoral research fellowship at Columbia in 2019, using MRI scans to study the brain activity of children with ADHD. She was struck by the fact that children as young as two or three were already having behavioral and emotional difficulties.

“I really wanted to understand what was happening earlier in their development to trigger these difficulties,” she says. “You can’t get much earlier than pregnancy.”

Pregnancy and sleep

In her study published last year, Lugo-Candelas used data from a National Institutes of Health study that included information on 794 pregnant women and their children. When women slept fewer hours during the second trimester of pregnancy, the data revealed, they were more likely to report that their child had problems with ADHD, sleep, or emotional regulation at age four.

“The evidence is pretty convincing that maternal distress during pregnancy can impact brain development in utero and set children up for difficulties,” says Lugo-Candelas. “What was new with our work was this focus on maternal sleep as a mediator of stress. Poor sleep may alter hormones and immune signals that in turn alter brain development.”

But exactly how stress passes from one generation to the next is unclear. Early results suggest that it is likely a combination of the environment in the womb—hormones and other signaling molecules—as well as changes to how DNA is packaged inside cells.

“We only have inklings of the mechanisms right now,” says Lugo-Candelas. “I’m really interested in creating a better picture of how this is happening.”

With the Irving Scholar support, she is now tracking levels of melatonin (a sleep hormone) and cortisol (a stress hormone) during women’s pregnancies. Ultimately, she hopes to find patterns between these molecules and children’s brain development to explain how maternal sleep and stress in pregnancy exert their effects on the next generation’s neurodevelopment.

Targeting health disparities

When designing her studies, Lugo-Candelas is mindful of including women and children from all socioeconomic and ethnic backgrounds.

“There is stress everywhere, but you may not see the full extent of the impact if you limit your population,” she explains. “People with the most resources and support may be somewhat buffered from the biological impacts of their stress.”

Ultimately, if Lugo-Candelas can piece apart the complex relationships between stress, sleep, and children’s neurodevelopment, she may be able to guide policymakers to develop interventions that optimize women’s health during pregnancy. To her, that means more than just telling women to get quality sleep.

“Telling an individual person to get more sleep is fine, but if we have loud and polluted environments that are preventing them from getting sleep, we need to deal with that,” says Lugo-Candelas. “Or if someone is a shift worker, or lives in public housing and can’t control the heat in their apartment. Those things take the blame off the individual and put them in a broader societal context.”

At the end of the day, Lugo-Candelas hopes her research helps minimize health inequities between socioeconomic classes and racial and ethnic groups. If she can stop stress and trauma from impacting the next generation, that may have larger ramifications for health. She admits that poor sleep is just one of many stresses that influences fetal growth and childhood health, but it is one that could be changed.

“What keeps me excited and motivated is that there is so little work done out there on this topic, especially within the Latino population,” she says. “It’s uncharted territory and so even if research moves slowly, every bit of progress is exciting.”