Stress influence on real-world driving identified by monitoring heart rate variability and morphologic variability of electrocardiogram signals: the case of intercity roads

Abstract

Objectives. This study examines which of the heart rate variability (HRV) and morphologic variability (MV) metrics may have the highest accuracy in different stress detection during real-world driving. Methods. The cross-sectional study was carried out among 93 intercity mini-bus male drivers aged 22–67 years. The Trillium 5000 Holter Recorder and GARMIN Virb Elite camera were used to determine heart rate and vehicle speed measurements along the path, respectively. We considered the HRV and MV metrics of electrocardiogram (ECG) signals including the mean RR interval (mRR), mean heart rate (mHR), normalized low-frequency spectrum (nLF), normalized high-frequency spectrum (nHF), normalized very low-frequency spectrum (nVLF), difference of normalized low-frequency spectrum and normalized high-frequency spectrum (dLFHF), and sympathovagal balance index (SVI). Results. The analysis showed that the HRV metrics mHR, mRR, nVLF, nLF, nHF, dLFHF and SVI are effective in mental stress detection while driving as compared to rest time. We obtained a high accuracy of stress detection for MV metrics as compared to the traditional HRV analysis, of approximately 92%. Conclusions. Our findings indicate that driver stress could be detected with an accuracy of 92% using MV metrics as an accurate physiological index of the driver’s state.

KEYWORDS:

• mental stress
• heart rate variability
• morphologic variability
• driving

Acknowledgements

The authors would like to express special thanks to all the experts and mini-buses drivers on the Tehran–Bumehen route for giving up their time for this research. The funder had no role in the design of the study and collection, analysis and interpretation of data and in writing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethical approval and consent to participate

The study protocol was reviewed and approved by the research ethics board of Iran University of Medical Sciences (Approval ID: IR.IUMS.REC.1398.080), Tehran, Iran. Written informed consent was obtained from all participants included in the analyses, and the project was conducted according to the World Medical Association Declaration of Helsinki.

Additional information

Funding

This work was supported by The Occupational Health Research Center, Iran University of Medical Sciences, Tehran, Iran [Grant No. 97-4-34-13830].