In a three-year study of more than 25,000 workers, Japanese researchers discovered that people who sat in front of computer screens were more likely to experience physical pain such as eye and shoulder strain, and to suffer from motivational symptoms such as lethargy.
Although workers are spending an increasing amount of time in front of their computers, no consistent guidelines exist about how long is safe to sit at a computer screen.
The study, led by Dr. Tetsuya Nakazawa and published in the November issue of the American Journal of Industrial Medicine, found that workers who spent more than five hours per day in front of a computer screen reported significantly higher complaints of sleep-related symptoms and mental stress.
Such symptoms included lethargy, anxiety, "difficulty getting along with co- workers," and a "reluctance to go out to work."
There was no time limit that triggered complaints of physical pain--the most commonly documented symptoms associated with computer use in the study. Workers most often reported symptoms such as eyestrain, headaches and stiff shoulders.
"Our results suggest that physical symptoms increase with duration of daily VDT (visual display terminal) use without threshold, while mental- and sleep-related symptoms increase with VDT work of more than five hours per day," the researchers wrote.
The researchers urged more studies of the link between computer use and physical and mental symptoms.
