Stress and hair cortisol concentrations in nurses during the first wave of the COVID-19 pandemic

During the COVID-19 pandemic, frontline healthcare workers have been exposed to very stressful conditions. Measuring hair cortisol concentrations (HCCs), which reflect the integrated long-term cortisol levels, may elucidate the impact of COVID-19 related stress on healthcare professionals. In the current study, we investigated experienced stress in 693 healthcare workers, with hair samples for cortisol analysis collected from a subset of 67 female nurses. The HCCs in two 3 cm hair segments corresponding to periods before and during the peak of the first wave of COVID-19 were compared. To evaluate the effect of working in the first line, the sample was divided into two groups based on the COVID-19 risk estimated by the nurses. Covariates in the model included perceived stress (PSS), perceived social support (MSPSS), and quality of sleep (PSQI) measured via an online questionnaire. The data showed that more than 75% of healthcare workers agreed that COVID-19 led to increased stress at their workplace. The hair cortisol analysis showed higher HCCs in the hair segments corresponding to the time of the pandemic compared to hair corresponding to an earlier period (partial η(2)(90%CI) = 0.123–0.397); in the same model, higher HCCs were also found in nurses from high-risk environments compared to low-risk ones (partial η(2)(90%CI) = 0.002–0.176). None of the subjective questionnaire measures were significant predictors of HCCs. In conclusion, these data showed that HCCs reflect the increased stress among nurses during the COVID-19 pandemic as well as the difference in nurses between high- and low-risk environments.