Physiological and psychological impacts on male medical interns during on-call duty

This study aimed to explore the physiological and psychological impacts on male medical interns during on-call duty (OCD). A prospective study of 13 medical interns was carried out using repeated testing during an on-call internal medicine and a duty-free course. There are 10 OCDs per month and each duty is composed of 33.5 consecutive work hours followed by 2 duty-free days for a time period of 3 months. Spectral analysis of R-R intervals was performed to evaluate the participants' heart rate variability. Among the three main spectral components distinguished, a high-frequency (HF) component of 0.15-0.4 Hz and a low-frequency component (LF) of 0.04-0.15 Hz were analyzed. The ratio of LF and HF (LF/HF) was also calculated. Reduced LF/HF, which suggests reduced cardiac sympathetic modulation, was found during duty night work. Increased HF was identified during the first sleep after OCD, which corresponded to the sleepiness scales. The OCD causes temporary emotional influence by the findings of higher anxiety and depression scores. In addition, inattention and impulsiveness, as represented by the continuous performance test score and lower nocturnal sympathetic modulation, were found, which indicated the differences between the internal medicine course and duty-free course. Our study suggests that 10 stressful on-call duties monthly result in reduced sympathetic modulation during duty night work, high anxiety and depression state, and a persistent inattention.