Don’t sleep on population health science

Justin Denney holding an open book at his desk.
Justin Denney, a population health scientist at Washington State University.

It’s not just chance, who is healthy and who isn’t. There are patterns, and the patterns are often far beyond an individual’s control.

Finding patterns in health and wellbeing is population health scientist and William Julius Wilson Distinguished Professor Justin Denney’s specialty. But his work doesn’t stop there. He then finds explanations for those patterns and builds community partnerships to change any policies that are causing inequities in health and wellbeing. In doing so, he is adding to the abundance of Washington State University research that directly impacts communities in Washington and the world.

Social and economic factors affect every aspect of health and wellbeing. They even affect sleep. Along with others at WSU, Denney co-authored a 2023 SSM – Population Health study that documented how sleep duration affected mortality risk in different racial and ethnic groups.

Evidence and guidance recommend sleeping between 7 and 9 hours each night. That, however, assumes sleep duration affects mortality risk in the same way across racial and ethnic groups. If that isn’t true, the recommendations could be causing people in some groups to make decisions that aren’t best for their health.

It’s difficult to find meaningful categories for people. “I wouldn’t say that conventional measures of race and ethnicity are a perfect way to categorize people but they do reveal important differences across groups,” says Denney. Race and ethnicity often correlate with social and economic factors, and those factors have a large impact on health and wellbeing.

Using data from the National Health Interview Survey, Denney found that sleep duration did affect mortality risk differently across racial and ethnic groups. Following the current sleep recommendations was associated with the lowest mortality risks for white people, but the associations for other groups were far less clear. For example, white people who slept less than five hours each night had greater mortality, which is in agreement with the recommendations. But that relationship was unexpectedly weaker for some racial and ethnic groups.

“Sleeping less than five hours a night is, generally speaking, not great for your health. Finding out that was the case more so for some groups than for others was surprising,” says Denney.

In partnership with medical facilities across the state, Denney and his colleagues are now turning to finding explanations. Then, he can move on to the final stage — providing evidence for policies that improve population health by breaking down the social and economic barriers that people in different racial and ethnic groups face.

Those policies extend far beyond the health system. Better education policies, for example, improve health. Safe and affordable housing policies improve health. Denney says, “All policy is health policy.”

By Vishva Nalamalapu, WSU Insider