How Poverty Shapes the Genetic Links Between Sleep and Mental Health

Research Spotlight Blog No. 12

Dr. Marina Xavier Carpena is a Visiting Professor at the Federal University of Rio Grande (FURG, Brazil), a postdoctoral researcher and collaborator of the Human Development and Violence Research Centre (DOVE) at the Federal University of Pelotas. Her research focuses on genetic epidemiology of mental and sleep traits, and how the role of socioeconomic adversity and biological vulnerability in shaping developmental outcomes. Marina is also committed to promoting inclusivity and diversity in global genetics research. 

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Why do some children seem more vulnerable to present both short/long sleep duration and mental health problems than others, even when growing up in similar environments? And how might poverty shape this vulnerability?

In my recent research, I explored how genetic risk and socioeconomic disadvantage combine to influence the relationship between sleep and mental health in children. Using data from two large population-based studies — one in Brazil and another in the United States — our team found that poverty can shape how genetic tendencies toward neuropsychiatric traits are expressed, particularly in how long children sleep.

The Puzzle of Genes, Sleep, and Environment

Genes play a role in shaping who we are — from our height to our mental health. But they don’t act alone. The environment we grow up in can either buffer or magnify genetic tendencies. For instance, supportive environments may reduce the impact of genetic risk for depression, while exposure to chronic stress, limited resources, or social inequality can make that risk more visible.

Sleep is one of the most powerful (yet often overlooked) pieces of this puzzle. Short or long sleep is both a symptom and a cause of mental health difficulties, and it is deeply influenced by the context of children’s lives — whether that’s noisy neighborhoods, unsafe housing, irregular routines, or parental stress linked to economic hardship.

Bringing Two Worlds Together: Brazil and the USA

To understand how genetics and environment come together, we compared children from the 2004 Pelotas Birth Cohort in Brazil — one of the few long-term population studies in Latin America — and the Adolescent Brain Cognitive Development (ABCD) Study in the United States.

These two contexts are very different: Brazil faces deep and persistent income inequality, while the U.S. has stronger social safety nets but still struggles with disparities in access to mental health care. Across both countries, we found a clear socioeconomic pattern in genetic liability: children from lower-income families had, on average, higher polygenic scores for ADHD, autism, and depression.

Including data from Brazil is a step toward more inclusive and equitable science

However, the interaction between these genetic risks and poverty revealed a more complex story. In the Brazilian cohort, poverty significantly altered the relationship between genetics and sleep. For instance, while a higher genetic likelihood for ADHD was generally associated with longer sleep, this effect was significantly weakened for children living in poverty. This suggests that socioeconomic disadvantage can suppress potential genetic advantages or amplify vulnerabilities, reshaping the link between our DNA and our health.

In the U.S. sample, a different pattern emerged for autism, where a higher genetic score was linked to shorter sleep, and this negative effect was even more pronounced in children living in poverty. The fact that these interactions were not uniform across disorders or countries highlights the profound context-dependency of genetic influences. Differences in social safety nets, the intensity of poverty, ancestry composition, and other unmeasured environmental factors likely all play a role in how genes and environments interact.

Why This Matters

These findings show that the impact of our genetics is not set in stone; it is shaped by our socioeconomic environment. This means that policies aimed at alleviating poverty and improving living conditions do more than just put food on the table—they can actively alter how genetic risks are expressed in a child's life. Tackling poverty is, therefore, a powerful form of intervention in the biological pathways that influence sleep and mental health.

They also underscore a critical flaw in modern genetics: most studies are based on populations of European descent in high-income countries. By including data from Brazil, our work is a step toward a more inclusive and equitable science, ensuring that genetic insights can one day benefit all of humanity, not just a privileged few.

Looking Ahead

Our next step is to understand the mechanisms through which socioeconomic factors and biology interact over time. The goal is to identify how improving children's environments can help "level the playing field." In this complex interplay, sleep stands out as a powerful, modifiable entry point—a potential bridge between the harsh realities of social conditions, the innate blueprint of our genetic makeup, and the ultimate goal of mental well-being for every child.

Blog by Marina Xavier Carpena