Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Mar 2;16(5):759.
doi: 10.3390/ijerph16050759.

The Effects of Indoor High Temperature on Circadian Rhythms of Human Work Efficiency

Guozhong Zheng  1 , Ke Li  2 , Wentao Bu  3 , Yajing Wang  4
Affiliations

The Effects of Indoor High Temperature on Circadian Rhythms of Human Work Efficiency

Guozhong Zheng et al. Int J Environ Res Public Health. .

Abstract

Indoor non-air-conditioned environments widely exist in the summer high temperature weather. The work efficiency of the people who stay indoors for a long time is seriously affected by the indoor high temperature. In this paper, the changes of the circadian rhythms of work efficiency in indoor high temperature environments were studied. Ten healthy subjects (five males and five females) were selected in the experiments randomly. In each experiment day, the maximum hourly outdoor temperature was selected as 28 °C, 32 °C, 36 °C, and 38 °C, respectively, to determine the experiment conditions. In each experiment condition, subjects' response time, accuracy rate, grip strength, work willingness, and physiological parameters were monitored for 24 consecutive hours. Meanwhile, the hourly outdoor temperatures of the experiment day were accessed from the weather report during the experiment. Then the cosinor method and statistical method were adopted. The results indicated that the response time, grip strength, and work willingness followed circadian rhythms. However, the accuracy rates of the Stroop color-word test (SCWT) and numeral inspection task (NIT) did not show an obvious circadian rhythm. The effects of high temperature on the circadian rhythms of grip strength and work willingness were mainly reflected in the decreases of the median and amplitude. The effects on the response time were mainly reflected in the decrease of the median. In addition, forehead temperature showed a significant negative correlation to response time, and it could be considered as a predictor to assess the level of work efficiency. This study gives an alternative method to replace direct measurement of the ability indices at work site and provides basic data of 24 consecutive hours, for showing changes in human work efficiency. It could be helpful to predict the low performance in advance to reduce occupational accidents.

Keywords: circadian rhythm; cosinor method; indoor high temperature; response time; work efficiency.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic diagram of the numeral inspection task (NIT).
Figure 2
Figure 2
Schematic diagram of the correct result of the SCWT test.
Figure 3
Figure 3
Schematic diagram of the false result of the SCWT test.
Figure 4
Figure 4
The mean values and standard deviations of the results of the physiological parameters: (A) Rectal temperature; (B) eardrum temperature; (C) forehead temperature; (D) heart rate; (E) systolic pressure; (F) diastolic pressure.
Figure 4
Figure 4
The mean values and standard deviations of the results of the physiological parameters: (A) Rectal temperature; (B) eardrum temperature; (C) forehead temperature; (D) heart rate; (E) systolic pressure; (F) diastolic pressure.
Figure 5
Figure 5
The relationships between: (A) Efficiency and arousal; (B) arousal and environment temperature.
Figure 6
Figure 6
The relationships between the response time and the temperature.
Figure 7
Figure 7
The mean values and standard deviations of the results of the work efficiency indices: (A) Response time-SCWT; (B) accuracy rate-SCWT; (C) response time-NIT; (D) accuracy rate-NIT; (E) grip strength; (F) work willingness.
Figure 7
Figure 7
The mean values and standard deviations of the results of the work efficiency indices: (A) Response time-SCWT; (B) accuracy rate-SCWT; (C) response time-NIT; (D) accuracy rate-NIT; (E) grip strength; (F) work willingness.
See this image and copyright information in PMC

References

    1. Brown F.A. The Biologic Clock. Academic Press; New York, NY, USA: 1970.
    1. Ma H., Yuan X.Y., Zhang C. Study on reaction time of operator under high temperature and high humidity environment. J. North Chin. Inst. Sci. Technol. 2014;11:68–72. (In Chinese)
    1. Sun X.C. Exercise Time Biology. Sichuan Education Press; Chengdu, China: 1993. (In Chinese)
    1. Wang X.Q., Jian K.L., Liu L. Study of circadian rhythms and its adjustment of tunnel gymnastics on reaction time of tunnel operators. J. Pla Inst. Phys. Educ. 2014;31:126–128.
    1. Perez J., Looze M.P., Bosch T., Neumann W.P. Discrete event simulation as an ergonomic tool to predict workload exposures during systems design. Int. J. Ind. Ergonom. 2014;44:298–306. doi: 10.1016/j.ergon.2013.04.007. - DOI

Publication types

LinkOut - more resources