Driver fatigue kills more people on the highways than texting, cell phone use and all other distractions combined. Yet the underlying factors of fatigue-related crashes have yet to capture the attention of Congress, the public and federal regulators. The WCNC-TV Investigative Team spent months drilling down into one cause that has received almost no national attention: sleep apnea. An estimated 13 to 20 million Americans suffer from sleep apnea and with increases in obesity which is related to the disorder, that number is climbing. Studies show drivers with sleep apnea are exponentially more likely to crash. And millions of long-haul truckers are more prone to sleep apnea than the average driver of a "four-wheeler".