Healthcare delivery frequently requires night duty, extended shifts and sustained high workload. These conditions may increase psychological stress while simultaneously reducing opportunities for sleep and physiological recovery. Occupational stress research increasingly recognizes that autonomic measurements should be interpreted in the context of work schedules, workload and recovery rather than as isolated physiological signals.1,3–5

HRV provides a non-invasive window into cardiac autonomic regulation. Lower RMSSD, SDNN and HF power commonly indicate reduced vagal modulation, although HRV is also influenced by activity, respiration, circadian timing and other individual factors.5–8 Continuous or repeated wearable monitoring is particularly suited to evaluating real-world occupational exposures because it can capture physiology during routine work rather than only in laboratory conditions.3,4,9

This study aimed to assess whether night-shift work, sleep duration and occupational workload were associated with differences in perceived stress and wearable-derived HRV among healthcare professionals.

This prospective observational study was conducted at a tertiary care teaching hospital from 1 April 2024 to 31 December 2025. One hundred healthcare professionals aged 21–60 years were included after written informed consent. Eligible participants included doctors, resident doctors, nurses, interns and other personnel directly involved in patient care. Major arrhythmias, implanted cardiac devices, acute illness, major autonomic-influencing conditions and inadequate wearable recordings were exclusion criteria. Participants underwent baseline demographic and occupational assessment followed by wearable monitoring during routine clinical duty. HRV analysis used normal-to-normal intervals after screening for artifact, ectopy and signal loss. Principal measures included SDNN, RMSSD, HF power and LF/HF ratio. PSS-10 was used to quantify perceived stress. Sleep during the preceding night was categorized as <6 hours, 6–7 hours or >7 hours. Occupational workload was categorized as low, moderate or high using duty duration, patient load, emergency/procedure burden, breaks and/or self-rated workload according to the study protocol. Day- and night-shift status was determined from the duty roster. Group comparisons used independent-samples tests or ANOVA/Kruskal-Wallis methods as appropriate. A p value <0.05 was considered statistically significant. Because HRV can be influenced by physical activity, age, BMI, caffeine, smoking, medications, sleep and time of day, these factors were documented for interpretation. The source thesis specifies prior Institutional Ethics Committee approval; the actual approval number should be added to the submission manuscript.

Of the 100 participants, 61 worked day shifts and 39 worked night shifts. Thirty-two participants reported <6 hours of sleep, 44 reported 6–7 hours and 24 reported >7 hours. Workload was categorized as low in 20, moderate in 48 and high in 32 participants.

Table 1. Comparison between day-shift and night-shift participants

Night-shift workers showed significantly greater perceived stress, higher heart rate, lower SDNN/RMSSD/HF power and a higher LF/HF ratio.

Table 2. Relationship between sleep duration and stress/HRV

Shorter sleep duration showed a dose-response association with higher perceived stress and poorer HRV. Participants sleeping >7 hours had the lowest PSS score and the highest RMSSD and SDNN.

Table 3. Relationship between occupational workload and stress/HRV

Increasing workload was associated with progressively higher PSS and heart rate and lower RMSSD and SDNN, demonstrating a clear graded pattern.

Night-shift duty was associated with significantly higher perceived stress and a less favorable autonomic profile. This finding is consistent with literature describing reduced autonomic recovery during stressful clinical contexts and the potential value of continuous HRV monitoring for tracking stress and recovery among doctors and other healthcare workers.1,4 Sleep duration showed a strong graded association with both PSS-10 and HRV. Sleep represents an important period of autonomic recovery; insufficient sleep may compound the effects of demanding work and circadian disruption. The source thesis notes that sleep is among the most frequently captured wearable variables in healthcare-professional well-being studies, reinforcing the need to interpret HRV together with recovery behavior.3 Occupational workload also demonstrated a dose-response pattern. RMSSD declined from 42.8 ms in the low-workload group to 23.6 ms in the high-workload group, while PSS rose from 16.2 to 26.2. These findings suggest that physiological monitoring gains meaning when combined with contextual measures such as patient burden, emergency activity, breaks and shift characteristics.3,4 The study's real-world design improves ecological relevance, but several limitations should be acknowledged. Observational associations do not establish causality. Night shift, workload and sleep are interrelated, and HRV can be influenced by physical activity, respiration, caffeine, medication, age, fitness and circadian timing.5–8 Wearable signal quality may also deteriorate with movement.9,12 Accordingly, HRV should be used as a complementary measure and not as an isolated indicator of worker performance or burnout.

Night-shift duty, inadequate sleep and high occupational workload were each associated with higher perceived stress and poorer wearable-derived HRV profiles among healthcare professionals. The graded relationships observed for sleep and workload suggest that occupational stress assessment should incorporate both physiological measures and contextual recovery/work-demand variables. Institutional strategies addressing excessive workload, night-duty recovery and adequate sleep may warrant evaluation in longitudinal interventional studies.

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