Because of peer pressure to keep up with co-workers, out-do competing groups and increase market-share at the expense of competitors, hundreds of thousand of Japanese managers are caught up in a vortex of psychological pressure that forces them to work at a frenzied pace.
After years of such intense over-work, most managers find that they cannot rest even when they do take time off. They are so wound up that not working leaves them disoriented and suffering from serious stress. More here
Also see the site of The office of the KAROSHI Hotline National Network
The office of the National Defence Counsel for Victims of KAROSHI