Workers at the Fukushima No. 1 nuclear power plant are facing an increased risk of accidents due to human error caused by chronic sleep deprivation and fatigue, an expert on social medicine said Wednesday in Tokyo, as he called for improved working conditions at the plant.

Ehime University professor Takeshi Tanigawa, who has visited the crippled power plant twice since the March 11 quake, said workers are getting only two days off every four days as they go about the trying task of keeping the nuclear reactors cool. Although they finally got separate beds last month, the workers still don't have proper shower facilities, he noted.

"I thought that sanitary conditions (for the workers) were not good," Tanigawa, who has worked part-time as a physician for Tokyo Electric Power Co. since 1991, said at the Foreign Correspondents' Club of Japan. When he first visited ground zero in April, the workers were having to share blankets.