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Updated: Mar 15, 2026

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
Published on: August 8, 2019
Fatigue and Sleep Among Employees With Prospective Increase in Work Time Control: A 1-Year Observational Study With
Tomohide Kubo1, Masaya Takahashi, Xinxin Liu
1National Institute of Occupational Safety and Health (Drs Kubo, Takahashi, Liu, Ikeda), The University of Tokyo Graduate School of Education (Dr Togo), The University of Tokyo Graduate School of Medicine, Tokyo (Dr Shimazu), Graduate School of Medical Science, Kitasato University (Dr Tanaka), Department of Psychiatry, School of Medicine, Kitasato University, Sagamihara (Dr Kamata), School of Nursing, Faculty of Medicine, The Jikei University, Tokyo (Dr Kubo), and Occupational Health Center, Yokohama Branch, RIKEN (The Institute of Physical and Chemical Research), Yokohama, Japan (Uesugi).
Objectives:
This observational study aimed to determine how 1-year changes in work time control (WTC) have an impact upon objectively measured fatigue and sleep among employees.
Methods:
Thirty-nine employees were divided into two groups according to whether or not their WTC increased from baseline to 1 year later. Psychomotor vigilance task (PVT) and wrist actigraphy were used to objectively measure fatigue and sleep, respectively. Self-reported outcomes were also measured.
Results:
The increased WTC group showed gradual improvements in PVT performance and sleep quality over the course of the follow-up period compared with the not-increased WTC group. Between-group differences were statistically significant for PVT lapses and tended to be significant for PVT speed after 1 year.
Conclusions:
A progressive increase in WTC could play a crucial role in reducing fatigue and promoting sleep among employees.
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