Americans in general do not sleep well. But those who sleep the worst live in the South, according to a new study by the Journal of Clinical Sleep Medicine. 24/7 Wall St. looked at the six states with the highest rates of sleep disturbance and identified a number of quality of life indicators that may help residents of some states sleep better than others.

Read the Six Worst States for Sleep

The researchers characterize sleep disturbance as “problems falling asleep, problems staying asleep, and/or sleeping too much.” According to the study, the states with the highest rates of sleep disturbance have a number of other traits in common. “Regional differences in sleep disturbance could be explained by a number of factors, the strongest of which being differences in mental and physical health, healthcare access, smoking, latitude/longitude and body mass index,” Dr. Michael Grandner, lead author of the study, told 24/7 Wall St.

The data 24/7 looked at certainly supports Dr. Grandner’s explanation. Obesity, as measured by body mass index, is high in all six states with the poorest sleep. Three of the states have the absolute highest obesity rates in the country, and the other three are in the top 12. Obesity often implies poorer health. All six states with the worst sleep are also among the top 11 states with the highest smoking rates among adults. West Virginia, which has the highest rate of sleep disturbance, also has the highest rate of smokers in the country.

Income may also be related to sleep disturbance, although this is not mentioned in the study. There are well-established relationships between low income and mental and physical health. Five of the six states with the worst sleep are also among the 10 states with the lowest median household incomes in the country, and the sixth falls among the lowest 15.

The researchers of the original report identified the states with the highest rates of sleep disturbance by asking 157,319 participants from 33 states a number of questions regarding the quality of their sleep in the 14 days leading up to questioning. In addition to the data published in the Journal of Clinical Sleep Medicine, 24/7 Wall St. looked at data from the Census Bureau, the Centers for Disease Control and Prevention and the American Human Development Project.

These are the six worst states for sleep.