It’s pretty intuitive that being underpaid and overworked leads to psychological distress.

A huge body of public health research backs up this intuition by observing a strong link between mental illness and socioeconomic status. Socioeconomic status in turn tracks pretty closely to who works hardest and gets paid the least, who has the fewest spare hours and resources to care for themselves, and who is most alienated from their work, often performing rote tasks under strict supervision.

A new paper published in the journal Epidemiology affirms the linkage, but argues that the research to date is limited by its emphasis on surface markers of socioeconomic status, like income, education, and occupational prestige. The study’s authors contend that to really understand the social causes of mental illness, researchers need to look under the hood at the process that gives rise to socioeconomic stratification to begin with: exploitation.