Multiple news outlets are reporting today that undiagnosed obstructive sleep apnea (OSA) may have played a role in the commuter train crash that occurred on Sept. 29, 2016, in Hoboken, N.J. According to a Reuters report, the train engineer was diagnosed with OSA in the weeks following the crash, which killed one person and injured 110 more. A common symptom of OSA is excessive daytime sleepiness.

On Oct. 13, the National Transportation Safety Board released its preliminary report on the investigation of the accident, which was caused when the train failed to stop, overrode a bumping post at the end of the track, and struck a wall of the NJT Hoboken Terminal. Engineer-induced emergency braking occurred less than 1 second before the collision with the bumping post. The engineer said that he remembers waking up in the cab, laying on the floor after the accident, but he has no memory of the event. The NTSB has not yet determined a probable cause of the accident.

Undiagnosed sleep apnea also played a role in a Metro-North train derailment in New York in 2013. That train’s engineer was found to have undiagnosed, severe OSA, and the probable cause of the accident was determined to be the result of his having fallen asleep while operating the train.

Overhead photograph of the damaged controlling cab car following the accident. A beam in from the station is shown in the front portion of the car. Taken on October 5, 2016. (National Transportation Safety Board)