Investigators have found that the driver of a Metro-North Railroad train wasn’t fully alert moments before the train rounded a curve at almost three times the speed limit and jumped the tracks, killing four people and seriously injuring 11, said a person familiar with the probe.

The driver, William Rockefeller, 46, wasn’t paying attention, based on statements he made to interviewers moments after the incident, claimed an anonymous tipster because details of the federal investigation aren’t yet public. It’s not yet known whether the driver was asleep, the person said.

The Dec. 1 crash caused the first passenger deaths ever for the commuter service when the train bound for New York’s Grand Central Terminal derailed while traveling 82 miles per hour on a 30-mph (48 kilometer-per-hour) curve, the U.S. National Transportation Safety Board said yesterday.

Sleep disorder expert R. Bart Sangal M.D. of the Sterling Heights Sleep & Attention Disorders Institute weighed in: “With the details beginning to emerge in this case, it’s highly likely that Rockefeller was driving while fatigued or drowsy.  It’s important to remember that drowsy driving is equivalent to driving while intoxicated- reaction times slow down, poor judgment is exercised,  attention declines, with decreased alertness and problems with short term focus and memory.  Drowsiness is the last step before falling asleep, not the first- as such, drowsiness means you are mere moments from falling asleep.  It’s obvious that operating machinery or driving in this state is highly dangerous.”

According to the National Sleep Foundation, signs of drowsiness while driving may include:

• Turning up the radio or rolling down the window
• Impaired reaction time and judgment
• Decreased performance, vigilance and motivation
• Trouble focusing, keeping your eyes open or your head up
• Daydreaming and wandering thoughts
• Yawning or rubbing your eyes repeatedly
• Drifting from your lane, tailgating and missing signs or exits
• Feeling restless, irritable or aggressive

The National Highway Transportation Safety Administration estimates 100,000 crashes reported to police each year are caused by driver fatigue, resulting in 1,500 deaths and 71,000 injuries. Additionally, the AAA Foundation for Traffic Safety conducted a study that found younger drivers — ages 16-24 — were nearly twice as likely to be involved in a drowsy driving crash than drivers ages 40-59. About 57 percent of drowsy driving crashes involved the driver drifting into other lanes or even off the road.

One culprit for drowsy driving could be undiagnosed obstructive sleep apnea (OSA), says Sangal.

An estimated 18 million Americans are affected by OSA — which causes constant sleep disruptions — and only about 30 percent of sufferers are diagnosed. According to Sangal “the constant state of sleep disruption associated with obstructive sleep apnea, is linked to the dangerous state of drowsy driving.”

Sangal urges anyone who thinks they or a loved one might have OSA or daytime sleepiness to schedule an appointment for evaluation at his Sleep & Attention Disorders Institute in Sterling Heights, MI. Call 586-254-0707 to schedule an appointment.