Federal officials said the same medical condition caused two major train accidents in and around the city.
The National Transportation Safety Board said engineers at the helm of a deadly crash in Hoboken nearly a year ago, as well as a crash in January in Brooklyn, both suffer from severe sleep apnea.
The NTSB said similarities between the two incidents led it to combine its findings into a single report.
A woman was killed and more than 100 were hurt when a New Jersey Transit train slammed into a platform at Hoboken Terminal last September.
More than 100 people were hurt back in January when a Long Island Rail Road train hit a post at the end of the tracks at Atlantic Terminal.
The MTA said shortly after the Brooklyn crash it would expand its program to treat employees with sleep apnea.
The Federal Railroad Administration announced last month it would no longer push regulations requiring engineers get tested for the disorder.