The FMCSA and the trucking industry knows how dangerous sleep apnea is for a truck driver. The FMCSA states HERE that: 

Staying awake means staying alive. Sleep apnea is a major contributor to daytime drowsiness—a condition that could prove deadly for commercial truck drivers and everyone sharing the road with them. It is a condition where, during sleep, a narrowing or closure of the upper airway causes repeated sleep disturbances leading to poor sleep quality and excessive daytime sleepiness. Since excessive sleepiness can impact a driver’s ability to safely operate the commercial vehicle, it is important that drivers with sleep apnea are aware of the warning signs.

The research arm of the American Trucking Association (ATA), American Transportation Research Institute (ATRI), states that sleep apnea exists in almost 1/3 of commercial driver and contributes to wrecks. See the white paper HERE.