Yesterday I higlighted Steve Bogira's latest for the Reader, about homicide and public health in Chicago; I've used the data set Bogira got his numbers from before, so I'm always curious to see what people do with it. Thanks in part to CeaseFire and Alex Kotlowitz and Steve James's coverage of it, we've gotten more used to thinking about violence as a public health issue, and to see the connections between violence, health, and poverty. Today the New York Times uses some interesting research out of Chicago to examine another facet of these interactions: sleep.

The latest evidence that race and ethnicity can affect sleep came in June at the annual meeting of the Associated Professional Sleep Societies, held in Boston. In one of two studies on the topic presented there, white participants from the Chicago area were found to get an average of 7.4 hours of sleep per night; Hispanics and Asians averaged 6.9 hours and blacks 6.8 hours. Sleep quality — defined as ease in falling asleep and length of uninterrupted sleep — was also higher for whites than for blacks.

Unsurprisingly, the researchers tie it back in to a familiar topic:

Because Chicago is still a fairly segregated city, “the blacks and Hispanics in our study were generally living in neighborhoods that are closer to freeways, so you have freeway noise, there’s more business noise at night, and there’s potentially more crime, which is stressful to people,” Dr. Carnethon said. People in lower-income neighborhoods are also more likely to have multiple jobs or to work odd hours, which can interfere with sleep.

Proximity to highways is harmful for a lot of reasons beyond sleep:

Traffic is also a significant pollution source for East St. Louis residents, as the city sits at the intersection of three interstate highways and U.S. Highway 40. Westbound traffic is often funneled into a single lane across the Mississippi River, which means traffic is constantly jammed and engines idle on the highways throughout the day. Also, because it’s a low-income area, local traffic consists of older and more polluting cars and buses.

The region’s levels of ozone and particulate matter, two pollutants caused by both automobiles and industry, exceed national air quality standards.

Of course, poor health can exacerbate sleep problems, another aspect the researchers mention. There's also the interplay with stress, which leads to less sleep, which causes stress, which impedes learning and increases aggression. Sleep's just a small piece of the puzzle, but it's an important addition to how these things are intertwined.

Photograph: Daehyun Park (CC by 2.0)