A 31-year-old male driver briefly fell asleep at the controls of a commuter train traveling at 120 kilometers per hour (75 mph) in the Tokyo metropolitan area in September, the railway operator said Tuesday.
Keikyu Corp. said the case came to light after a female passenger alerted the company by email that the driver appeared to be dozing on the train.
According to Keikyu, the driver briefly slept while operating the limited express on the main line between Keikyu Kawasaki and Kanazawa-bunko stations, on Sept. 24.
The driver admitted to falling asleep on duty, saying he felt sleepy several times while running the train on the section for 23 minutes.
Keikyu said it plans to punish the driver.