Study on the establishment of the effective occupational health management system in shift workern -analyzing the heart rate variability-

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11670335
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Hygiene
• Research Institution: University of Tsukuba, Institute of Community Medicine
• Principal Investigator: MATSUZAKI Ichiyo University of Tsukuba, Institute of Community Medicine, assistant professor, 社会医学系, 講師 (10229453)
• Project Period (FY): 1999 – 2000
• Keywords: shift work / heart rate variability / occupational health management / karoshi

Research Abstract

Purpose : We investigated the influences of shift work---the imbalance of individual autonomic nervous function. the change of the adaptation process and the characters of the external factors about the diseord. Also we investigated the relation between the results of autonomic nervous system and subjective symptoms. considering the health practice of the worker. We also considered effective work schedules and lifestyle guidance based on this study.
Subjects : We studied 124 men working at a steel pipe manufacturing plant.
Results ＆ discussion :
1. Measurement of heart rate variability and the automatic nervous function
Sympathetic nerve system was superior between work-time while parasympathetic nerve system was superior between steep-time. Activity of sympathetic nervous system between sleep-time on the 2^<nd> night-work was significantly lower than that of the 3^<rd> day-work. Also the activity of sympathetic nervous system between sleep-time on the 4^<th> night-work elevated as high as day-work. We supposed there was an adaptation process in autonomic nervous function in shift workers.
2. Questionnaire study
There was no difference in subjective symptoms between work styles. Sleep improved in the 4^<th> night-work than in the 2^<nd> night-work. Also, shift workers were better in the mental and physical health than day-workers researched by General Health Questionnaire (GHQ). We considered that the factors, with may influence the GHQ score, are the custom to the shift-work and work environment during day and night-time. Day-worker had good health practice about their lifestyle shown by Health Practice Index (HPI) results. These was no difference between work styles shown by Work Stressor Check list (WSC) results.
3. Retrospective study about the blood pressure of shift worker
There was no difference about Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) between work styles. We considered that these results might be a manifestation of healthy worker effect.
4. Intervention study
There was no difference about SBP and DBP between work styles. But subjective symptoms, sleep and health practice were improved significantly.
Conclusion : We were able to classify the adaptation process about autonomic nervous systems in shift work and recovery from night work at the point of sleep. And we were able to improve in the subjective factors by our intervention.