Sleep is regarded as one of the foundations of health along with exercise and nutrition.^1,2 Sleep is essential for the maintenance of many bodily processes, including immunity, metabolism, hormone balance, and cardiovascular health.³ Adults should get seven to nine hours of sleep every day, according to the "National Sleep Foundation" and "The American Academy of Sleep Medicine."^2,3 Sleep regulation takes place in the brain and is controlled by the hypothalamic suprachiasmatic nuclei (SCN), which in turn controls the sleep/wake cycle. Medical staff working on shift duty sleep during the day and work at night thereby disturbing the body's natural sleep cycle.⁵ The circadian rhythm controls a number of vital physiological parameters like heart rate and blood pressure.^6-11

Medical staff provide round-the-clock patient care by working in shifts. Work schedules that use three or more time slots to provide full 24-hour coverage and split the day into roughly equivalent segments are referred to as shift work.^4,5 Altered sleep is the most frequent health problem shift workers encounter.^5,12 Sleep alteration can result in dysregulation of the autonomic nervous system. This dysregulation could lead to an alteration in blood pressure and heart rate. Furthermore, inconsistent sleep and work schedules could affect respiratory patterns and alter respiratory rate.¹³ Thus posing a higher risk of hypertension, cardiovascular disease, and cerebrovascular disease due to altered sleep.^3,14,15

Even though medical staff plays a vital role in maintaining others' health, there remains a knowledge gap regarding the impact shift work has on the cardio-respiratory parameters. The physiological effects of erratic work schedules on the medical staff require further examination to guarantee the preservation of their personal well-being and, in turn, the standard of care they deliver. By exploring the complex relationship between shift work and cardio-respiratory parameters in medical staff, this study seeks to close the current knowledge gap. Through exploring this unexplored area, we aim to identify the particular physiological effects that might result from rotating shift work schedules. This research is important because it will help us better understand how shift work affects medical staff health. It will help shape practices and policies that can lessen any negative effects.

The study aims to compare various cardio-respiratory parameters in medical staff working on shift duty and day duty.

Study Design and Participants

The Institutional Ethics Committee of the Parent Institute approved the study. The ethical guidelines for biomedical research on healthy participants published by the ICMR in 2006, the 2013 Declaration of Helsinki, and the ICH-GCP Guidelines were all followed in the conduct of the study. The research, which was classified as "cross-sectional," lasted for eight months, from September 2023 to May 2024. Subjects between the ages of 25 and 40 were selected from the Parent Institute. At a 95% confidence level and 80% power level, the research conducted by other authors led to the minimal sample size of 34 being determined. 

Two equal groups of all 200 medical staff members were involved in the study. One hundred medical staff working rotating shifts made up the study group while those working during the day made up the control group.

Inclusion criteria

The medical staff working for at least 7 hours per day for 6 days in a week in the daytime at the parent institute.

The medical staff working for two-morning shifts, two evening shifts, and two-night shifts for at least 7 hours per day for 6 days in a week at the parent institute.

Exclusion criteria

Subjects who were aware of their sleep issue and receiving therapy. Subjects who refused to provide consent. Subjects taking medications for hypertension or for lowering lipid levels, Subjects with known cardiac or respiratory problems. Women who are pregnant or nursing. Subjects having any past medical history like skeletal anomalies. Subjects with a past history of any surgery. Subjects with insomnia and depression were all excluded from the study.

Data Collection

Non-random sampling was used to choose subjects from the Parent Institute who were between the ages of 25 and 40 years. Two equal groups of all 200 medical staff members were involved in the study. After it was translated into the local language, informed consent was obtained. A general history was obtained from the chosen subjects. Three hours before the test, the subjects were requested to abstain from eating or drinking anything caffeinated and to dress comfortably and loosely. All of the recordings were done in a calm, naturally lit room with good ventilation at the Parent Institute between the hours of 4 and 6 p.m. and 9 and 11 a.m. The data was collected using a mercury sphygmomanometer.

Statistical Analysis

After the data were entered into MS Excel 2021, SPSS-16 software was used to analyze them. For numerical data, descriptive analysis used the mean and standard deviation (SD), whereas frequency and percentage were used to convey categorical data. To compare the means of the two groups, an unpaired t-test was employed.

A statistically significant P value was defined as one that was less than 0.05

Every participant in the research completed the test in its entirety. Two equal groups of 200 medical staff members were created, one was the study group and the other as the control group. The study group's members worked shift duty. Males and females between the ages of 25 and 40 years made up the study participants. The average age of the study group participants (N = 100) was 31.9 years, while the control group participants (N = 100) had an average age of 33 years. The research group comprised 64 males (64%) and the control group comprised 36 females (36%). Regarding age and gender, there was no significant difference between the groups (P > 0.05). (Table I)

Table I: Sociodemographic information of the medical staff working in shifts and day duty.

(Unpaired t-test)                                                                                                                 (p < 0.05 = significant)

The Mean Heart rate in the study group was 77.6 ± 1.9 beats/min and in the control group, it was 71.6 ± 1.9 beats/min. The Mean Systolic Blood Pressure (SBP) in the study group was 126.9 ± 1.4 mmHg while in the control group it was 120.2 ± 1.6 mmHg. The Mean Diastolic Blood Pressure (DBP) in the study group was 85 ± 1.2 mmHg while in the control group it was 80.8 ± 1.1 mmHg. The Mean Respiratory Rate (RR) in the study group was 13.5 ± 0.8 breaths/minute while in the control group it was 12.6 ± 0.7 breaths/minute. The mean Heart rate, mean SBP, mean DBP, and mean RR were significantly higher in the study group as compared to the control group (P < 0.05). However, there was no significant clinical difference observed in respiratory rate. (Table II)

Table II: Information about HR, SBP, DBP, and RR of Medical Staff participating in the study.

This study included medical staff working on shift duty as well as staff working on day duty. Sleep is a vital component of life, and any alteration to sleep can cause disruptions to a number of physiological processes in the body.³ The results of the study shows a significant increase in cardiorespiratory parameters i.e., heart rate, systolic and diastolic blood pressure, and respiratory rate  in medical staff working in shift duty as compared to medical staff working on day duty. These results are in line with Gamboa Madeira S et al., (2021) which showed an increase in systolic blood pressure in rotating shift workers and an increase in systolic and diastolic BP in workers working in night shift only.¹⁶ Another study by Chaitra ND et al., (2020) showed an increase in systolic BP and diastolic BP in healthy nurses working on shift duty.¹⁷ Meng R. et al., observed a result in line with our research showing an increase in blood pressure in shift workers in females aged 31-40 years.¹⁸ The study from Monteze NM et al., (2015) revealed an increase in systolic BP and diastolic BP in shift workers.¹⁹ The human body experiences a 24-hour rhythmic change in blood pressure, which peaks at noon and then gradually declines again at 4:00 AM. There is a dipper pattern, with daytime high blood pressure and night-time low blood pressure.²⁰  A possible mechanism for the variation in blood pressure among medical staff could be the disruption of the circadian rhythm and shorter sleep durations.^21,22 Compared to medical staff working on day duty, shift duty medical staff are more likely to be categorized as non-dippers.²³ Having a night shift disrupts the typical BP diurnal rhythm.²⁴ Studies have shown that working night shifts raise sleeping blood pressure more than working day duty. Severe sleep deprivation has been related to higher sympathetic nervous system activity, which raises heart rate and blood pressure.²⁵ Further affecting these parameters is a state of heightened physiological arousal brought on by the inherent stress related to the unpredictability of medical emergencies during different shifts. It has been demonstrated that shift work interferes with the release of hormones that are essential for controlling cardiovascular function, such as melatonin and cortisol. The observed variations in heart rate and blood pressure could be attributed to the dysregulation of these hormonal profiles. Moreover, elevated blood pressure may be a result of the renin-angiotensin-aldosterone system activation, which is frequently linked to stress.¹⁸

This study gives insights on various clinical implications which are as follows

Hospital Workforce Optimization: Hospitals can optimize workforce scheduling by having a thorough understanding of the unique cardio-respiratory implications associated with shift work. Establishing patterns that lead to negative physiological consequences can help facilities create more health-aware schedules that put the health of their medical staff first. Thus, among healthcare workers, there may be a decreased chance of respiratory and cardiovascular problems. 2. Risk Assessment and Early Intervention: Based on the research, risk factors related to rotating shift work are evaluated. Recognizing medical staff who are more susceptible to cardio-respiratory problems enables focused health monitoring and early intervention. Timely interventions can potentially halt the progression of cardiovascular and respiratory disorders by detecting changes in blood pressure, heart rate, and respiratory rate early. Policy Creation for Healthier Work Environments: Based on the results, institutional policies and guidelines that aim to improve the working conditions for medical staff can be developed. This can entail suggestions for getting enough sleep in between shifts, the availability of designated rest areas, and techniques to lessen the negative effects of circadian rhythm disruption. Putting such policies into place can improve the medical staff's general well-being. 4. Enhanced Occupational Safety: For medical staff, cardio-respiratory health is essential to overall occupational safety. By addressing how shift work affects these parameters, safety protocols that take into account the physiological demands of the job can be established. This could involve ergonomic changes, focused training initiatives, and other steps to reduce the possibility of unfavourable health consequences. 5. Better Patient Care: A more robust and healthy medical staff is better able to deliver high-quality patient care. The physiological difficulties that come with working shifts may be resolved, which could enhance cognitive function, decision-making, and overall job performance for medical staff. Consequently, this can have a favourable impact on patient satisfaction and outcomes. 6. Preventive Health Measures: The research may help create customized preventive health plans for medical staff working on shift duty. This could entail putting wellness programs into place, making healthcare screenings accessible, and launching educational campaigns to encourage healthier lifestyle choices among medical staff. 7. Decrease in Healthcare Costs: Treating medical staff members' cardio-respiratory conditions early may result in lower medical expenses for treating work-related illnesses. Enhancing general health and preventing chronic illnesses can help make the healthcare system more affordable.

Limitations

The study's cross-sectional design limits our ability to establish causation.

This study found elevations in systolic BP, diastolic BP, heart rate, and respiratory rate emphasizing the importance of addressing the potential health risks associated with irregular working hours.

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