Previous studies have suggested that long-term elevated levels of cortisol, a stress hormone, may correlate to increased abdominal obesity, hypertension, diabetes and cardiovascular risk. Laura Manenschijn, from Erasmus Medical College (The Netherlands), and colleagues collected hair samples from 33 shift workers and 89 day workers. Cortisol was extracted from the hair samples, and cortisol concentrations assessed. The team found that long-term cortisol levels were significantly increased in individuals working in shifts, especially in study participants younger than 40 years. Reporting that: “Shift work at a young adult age is associated with elevated long-term cortisol levels and increased [body mass index],” the researchers warn that: “Elevated cortisol levels and [body mass index] may contribute to the increased cardiovascular risk found in shift workers.”