In previous studies, it has been determined that kids living in violent neighborhoods often perform poorly on tests. Researchers at Northwestern University’s School of Education and Social Policy recently looked at why in an attempt to explain this link and why it occurs.

The study, which was published in the journal Child Development, showed that the violent crime affected children’s sleep patterns, which increases levels of cortisol, a stress hormone.

Jenni Heissel, the study’s lead author, noted that sleep and cortisol are connected to the brain’s ability to learn and then perform academic tasks. By affecting quality of sleep, violent crime could find its way into affecting academic performance.

The researchers looked at the stress hormones and sleep patterns of 82 students, ranging from ages 11 to 18 years. The students attended different public schools in a Midwest city. The data showed that the day after a violent crime in the neighborhood, the students’ cortisol levels rose.

As a result, children in disadvantaged neighborhoods could face extra challenges academically. This data does not mean that children in more violent, inner-city neighborhoods cannot be successful in school. However, it helps pave the way for schools to implement techniques for helping students cope with stressful events.