Study: Air traffic controllers' lack of sleep puts passengers at risk

SAN FRANCISCO -- For more than three years, the U.S. government kept secret a study that found 75 percent of air traffic controllers' work schedules often lead to chronic fatigue, which made them "less alert" and "endangering the safety of the national air traffic system."

It revealed that many controllers are having trouble staying awake on the job, putting lives at risk.

According to the report, conducted by conducted by NASA in 2011, controllers reported an alarming lack of sleep. Close to three-quarters of the more than 3,000 surveyed said their schedules led to chronic fatigue.

In 2012, the FAA says it implemented a system to manage controller fatigue, including making changes to scheduling. They say that has improved the situation since the NASA report.