WHITE PLAINS, N.Y. (AP) -- An engineer driving a speeding commuter train that derailed last year, killing four people, had a sleep disorder that interrupted his rest dozens of times each night and said he felt strangely "dazed" right before the crash, according to federal documents released Monday.
Asked if he was clearheaded enough to realize he was entering a curve just before the Dec. 1 derailment in the Bronx, engineer William Rockefeller told investigators "apparently not."
The Metro-North Railroad train hit the curve, which has a 30 mph speed limit, at 82 mph. More than 70 people were injured.
The National Transportation Safety Board released medical reports, interview transcripts and other documents but said its analysis of the information and any determination of the cause would come later.
Rockefeller's medical exam after the accident uncovered "severe obstructive sleep apnea," apparently undiagnosed, the NTSB said. It said a sleep study had been ordered because Rockefeller "did not exactly recall events leading up to the accident."
The study found that while Rockefeller slept, he had about 65 sleep arousals per hour. Scientists say as few as five interruptions an hour can make someone chronically sleepy.
In his NTSB interview, two days after the accident, Rockefeller didn't describe himself as sleepy. He said his run from Poughkeepsie to Manhattan was without incident - with brakes, signals and the speedometer working fine - until a strange feeling came over him.
"It was sort of like I was dazed, you know, looking straight ahead, almost like mesmerized," he said.
He compared it to driving a car and staring at the taillights ahead and almost getting "that hypnotic feeling."
He said he couldn't be sure when the dazed feeling began, but he remembered seeing the Riverdale station, just before the Spuyten Duyvil station where the derailment occurred.
He said he was roused only when he sensed "something wasn't right" with the train and instinctively shut it off or threw it into emergency braking. He said he then felt the derailment and was "thrown around" before shouting "Emergency! Emergency!" several times into the radio, only to realize that because the key was out of the ignition the radio was off.
In separate interviews, the conductor and assistant conductors told investigators they didn't feel any sudden or unusual braking before the derailment. Assistant conductor Chris Kelly said, "It just felt like a routine coming around the corner."
The NTSB noted that sleep apnea is not mentioned in Metro-North's medical guidelines. It repeated its recommendations that Metro-North put more speed limit signs on the right of way and put audio and video recorders on the trains.
Metro-North, which operates trains in New York and Connecticut, said it's reviewing the new documents and will work with the agency on the recommendations.
Rockefeller's lawyer, Jeffrey Chartier, didn't immediately return messages seeking comment.
The report said Rockefeller's blood and urine tests after the accident revealed small amounts of aspirin and an over-the-counter antihistamine that carries a warning it could impair the ability to drive.
The report also notes Rockefeller's work schedule had recently changed from late night to early morning shifts.
Apnea is more common in those who are overweight, and the medical report describes the 5-foot-11 Rockefeller as obese. Records in the report indicate he was 274 pounds last year but down to 261 pounds after the accident.
The report says a sleep medicine specialist prescribed an apnea treatment known as CPAP, or continuous positive airway pressure, which uses a mask and hose to push a steady flow of air pressure into a person's airway during sleep.
Associated Press writer Michael R. Sisak and AP Writer Medical Writer Mike Stobbe contributed to this report.