FILE - In this Dec. 1, 2013 file photo, a Metro-North passenger train lays on it's side after derailing on a curved section of track in the Bronx borough of New York. Federal investigators say William... more 
FILE - In this Dec. 1, 2013 file photo, a Metro-North passenger train lays on it's side after derailing on a curved section of track in the Bronx borough of New York. Federal investigators say William Rockefeller, who was engineer on a New York commuter train that derailed last year, killing four people, has a serious sleep disorder. A medical document made available Monday April 7, 2014, by the National Transportation Safety Board says he has "severe obstructive sleep apnea." The NTSB did not say whether the engineer's disorder contributed to the crash.( (AP Photo/Mark Lennihan, File) less 
1 / 1
Associated Press | Photo By Mark Lennihan, File
Mon, Apr 7, 2014 4:00 PM EDT