"Terminal" Illness

Too Much Screen Time Can Make Computer Users Sick Reuters Health November 05, 2002

The more time an office worker toils in front of a computer, the more likely he or she is to suffer a host of physical, mental and sleep-related ills, Japanese researchers report.

While video display terminal (VDT) use has become commonplace in many types of jobs, there is little information on how long a person can safely use a computer each day. To investigate, Dr. Tetsuya Nakazawa of Chiba University and colleagues surveyed over 25,000 office workers who responded to three questionnaires between 1995 and 1997.

Participants answered questions about the amount of time they spent in front of a VDT, their sleep habits, and physical and mental ailments including headache, low back pain, eyestrain, depression and anxiety. Their findings are published in the October issue of the American Journal of Industrial Medicine.

"In our study, we found a significant relationship between duration of daily VDT use and physical symptoms," even after adjusting for other factors that could influence the results, the authors write.

Office workers stuck in front of a computer most commonly complained of headache, eyestrain, joint pain and stiff shoulders. Mental symptoms such as lethargy, anxiety and "reluctance to go to work," as well as sleep-related problems including insomnia and fatigue, were most common among workers who spent more than 5 hours a day glued to their computer screen.

"This result suggested that the effect of duration of daily VDT use on these scores has a threshold effect, and the prevention of mental disorder and sleep disorder requires the restriction of VDT use to less than 5 hours per day," the researchers write.

While the type of computer work the study participants performed varied considerably, as did the size of the computer used and the work environment, "it should be emphasized that even under such working conditions, our results were extremely consistent over a 3-year period," Nakazawa and colleagues note.

The researchers call for more research into the relationship between computer use and physical, mental and sleep symptoms.

SOURCE: American Journal of Industrial Medicine 2002;42:421-426 --------------------------------------------------------------------------------

Association between duration of daily VDT use and subjective symptoms

Tetsuya Nakazawa, MD 1 *, Yasushi Okubo, MD, PhD, Yasushi Suwazono, MD, PhD, Etsuko Kobayashi, PhD 1, Shingo Komine, MD, PhD , Norihisa Kato, MD, PhD , Koji Nogawa, MD, PhD Department of Occupational and Environmental Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan Shutoken Health Administration Center, Nippon Telegraph and Telephone East Corporation, Japan

Abstract

Background
Although visual display terminal (VDT) work has become a common task among office workers, surveys which would help to determine the allowable duration of daily VDT use are limited.

Methods
We investigated more than 25,000 workers three times over a 3-year period using a self-administered questionnaire. Three factors, namely mental, physical and sleep-related symptoms, were extracted by factor analysis. Adjusted means of each factor score were compared with the duration of daily VDT use by general linear model.

Results
Physical symptoms score became higher with increasing duration of daily VDT use without a threshold effect. Mental and sleep-related symptom scores of the workers using VDT for more 5 hr/day were significantly higher than that of the groups using VDT for >1, 1-3, and 3-5 hr/day.

Conclusions
Duration of daily VDT use was linearly related to the physical symptom score, and was non-linearly related to mental and sleep-related symptom score with a threshold effect of 5 hr/day.

Am. J. Ind. Med. 42:421-426, 2002. © 2002 Wiley-Liss, Inc. Accepted: 5 August 2002