A Study to Assess Changes in Cortisol Level and Heart Rate Variability between Fixed Duty and Shift Duty Health Care Providers in a Tertiary Care HospitalA Cross-Sectional Study

Introduction: Increased demand of service 24 hours around the clock has divided the workers into 2 domains as “Fixed duty” and “Shift duty”. Personals associated with shift duty are increasing in numbers day by day. Shift duty or more specifically night duty is associated with increased stress which results in high morbidity and decrease in work efficiency. Cortisol hormone and Heart Rate Variability (HRV) are useful parameters to determine the effects of stress.

Aim: To find any change in cortisol levels, HRV, Athens score among the fixed duty and shift duty healthcare providers.

Materials and Methods: A descriptive cross-sectional comparative study was conducted in a tertiary care hospital at Kolkata between July, 15th to Sept, 15th 2021. Predesigned and pretested questionnaire was made and ethical clearance was taken from institutional IEC. Then after taking consent total 120 (60 fixed duty and 60 shift duty) healthcare providers were recruited for the study. Subjects of the study filled up a questionnaire {including Athens Insomnia Scale (AIS)}. After applying exclusion criteria (any cardiovascular, neurological, psychological, sleep disorder) 120 health individuals were taken five minutes short-term HRV (time and frequency domain) recording in supine posture and 4 PM blood sample (for cortisol) were obtained from the participants which was further analysed in Chemiluminescence Immunoassay (CLI). Data was analysed in SPSS version 20.0. Statistical tests like student t-test, Cronbach’s alpha and Chi-square tests were applied significant p<0.05 (95% CI).

Results: After analysis, shift duty workers showed a significant (p<0.001, Odd’s 10.706) higher chance of having insomnia (Athens score >6) than fixed duty workers. Blood test showed that shift duty workers had significantly high evening cortisol level than fixed duty workers (p=0.036). The time domain of HRV showed that the parameters like Standard Deviation all NN interval (SDNN) (p=0.001), Mean HR (p=0.037), RMSSD (p<0.001), NN50 (p=0.006), pNN50 (p=0.002) were significantly different in the two groups. Whereas the frequency domain of HRV showed that HF power was lower and LF power (p=0.002), LF/HF ratio (p<0.001) were significantly higher in shift duty workers.

Conclusion: The study showed that shift duty workers had comparatively higher stress levels resulting in significantly high sympathetic drive and increased risk of insomnia. This can be associated with morbidity and ill-health in the shifting duty workers.