Key result
Shift work linked to reduced overall HRV and sympathetic tension indices versus rest.
Why the study?
Circadian rhythm disruption from shift work increases cardiovascular disease risk, but its effects on heart rate variability and circadian disruption in shift workers remain poorly understood.
Does shift work disrupt heart rate variability and autonomic nervous system circadian rhythms in shift workers?
Observational (n=30)
No
Does shift work disrupt heart rate variability and autonomic nervous system circadian rhythms in shift workers?
Shift work significantly reduces heart rate variability and disrupts the normal circadian rhythm of the autonomic nervous system, which may contribute to the increased cardiovascular risk observed in shift workers.
Answers are grounded in this paper and cite their sources.
Shift work-associated HRV reductions may indicate autonomic disruption and elevated CV risk; leaves open causal mechanisms and intervention targets.
Objective Circadian rhythm disruption caused by shift work increases the risk of cardiovascular disease, but its effects on heart rate variability (HRV) and circadian rhythm disruption in shift workers remain poorly understood. This study aims to observe changes in HRV in shift workers during shift work and during rest and to analyze its impact on the autonomic nervous system (ANS) and circadian rhythms. Method This study recruited 30 shift workers aged 23–50 from a medical center in Chengdu, China, during the period from January to September 2025. Wearable three-electrode Holter electrocardiogram patches were used to collect time-domain, frequency-domain, and nonlinear HRV metrics during shift work and during rest. By dividing the day into daytime and nighttime periods and calculating △HRV values to further investigate the diurnal variations in HRV and ANS following shift work. Results In the 24-hour analysis, it was observed that individuals experienced a significant decrease in overall HRV indices, including SDNN and S, as well as sympathetic tension indices such as SDANN and SD2, during shift work (P < 0.05). Further analysis by diurnal periods revealed that shift work was associated with significant reductions in overall HRV indices (triangular index, TINN, and S) during nighttime compared to rest in male youth (P < 0.05). In male shift workers, parasympathetic tone indicators (RMSSD, HF, and SD1) and sympathetic tone indicators (SDNNI) were significantly lower during nighttime compared to rest (P < 0.05), while showing paradoxical elevation during daytime (P < 0.05), exhibiting a circadian inversion opposite to normal rhythms. Furthermore, compared with resting conditions, no significant changes were observed in heart rate parameters (mean heart rate, maximum heart rate, and minimum heart rate) or arrhythmia parameters (ventricular premature beats and supraventricular premature beats) among shift workers after shift work (P > 0.05). Conclusion Shift work significantly reduces the heart rate variability of shift workers, suggesting a relative increase in sympathetic nervous system activity and being related to the normal circadian rhythm of the autonomic nervous system.
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Dan et al. (2026) conducted an observational in Shift workers (n=30). Shift work vs. Rest was evaluated on Overall HRV indices (SDNN, S) and sympathetic tension indices (SDANN, SD2) (p=<0.05). Shift work reduced overall heart rate variability indices (SDNN, S) and sympathetic tension indices (SDANN, SD2) compared to rest.
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