WASHINGTON (CBSDC) — There are certain regions across the United States where people aren’t getting enough sleep, according to a new study.

Researchers found that there are 84 “hotspots” across the nation where there are higher levels of insufficient sleep, and 45 “coldspots” where people tend to get more sleep, as reported by The Guardian.

“Sleep is more than a physiologic process. Understanding the context of sleep will help us understand how and where to target our efforts,” Michael Grandner, the study’s lead author and an assistant professor of psychiatry at the University of Arizona, told The Guardian. “It is possible that improving sleep at the population level will be key to improving the public health.”

The survey asked 432,000 participants how many days over the last 30 days they felt they got insufficient sleep. Researchers then placed those who reported sleeping poorly fewer than 15 days in one group, while those who reported sleeping poorly on 15 ore more days were placed in another group. Researchers said they chose these guidelines as they replicate the diagnostic criteria for insomnia.

Responses were then categorized by county to evaluate which areas had the highest levels of insufficient sleep.

Researchers found Kentucky, Tennessee, and West Virginia had counties with the highest levels of insufficient sleep. Over half of the counties that were considered “hotspots” fell at the intersection of these states. Other states that saw high levels of sleep deficiency were Ohio, Texas, and Missouri.

The study also found that the level of concentration for poor sleep was much higher than the level of concentration for sufficient sleep, with no findings of “coldspots” comparable to the intensity of “hotspots.” The few aggregations of sufficient sleep areas were found in Texas, northern Virginia, and northern Midwest.

When looking at numerous social and demographic factors, researchers found no correlation as to why people sleep less in certain areas. However, study authors note that younger individuals of lower socioeconomic status and poorer health were more likely to live in “hotspots.”

The findings are based off 2009 date from the Centers for Disease Control and Prevention as the analysis started in 2010. Researchers are hoping to follow up with more recent data in addition to exploring why these geographical differences exist.

“This is just a first step,” Gardner said. “Once we identify where these resources are directed, we can dig deeper to understand why these particular regions are hardest hit and what can be done about it.”