More than 40 New Jersey Transit train engineers have been sidelined after testing imposed in the wake of a deadly rail crash found that they suffered from sleep apnea.

The agency screened 373 engineers for sleep disorders in the past year, and 57 were taken out of service until a full study could be conducted.

News 12 New Jersey had learned that 44 engineers were confirmed to have sleep apnea and were sidelined until they met treatment requirements. Two of those engineers remain out of service.

The 13 other engineers were found to not have sleep disorders.

The testing followed a September 2016 crash in which a train slammed into Hoboken Terminal, killing a young mother and injuring more than 100 people. 

The National Transportation Safety Board found the engineer suffered from sleep apnea.

New Jersey Transit says that its statistics are consistent with national numbers. A spokesperson for the agency says that about 40 million Americans suffer from some sort of sleep disorder.