Many people leave their job at the end of the day complaining about how tired they are, so how many are just whining and how many are actually fatigued?

The National Sleep Foundation did a study to find out what professions were the most tired, and how it affected them.

It turns out that the transportation industry leads the "yawn-o-thon" which puts the rest of us at a higher risk.

One in 10 American truck drivers, train conductors, airline pilots and other transportation workers could be dangerously sleep-deprived.

Most said they feel drowsy while working, and some are worried their fatigue is a threat to commuter safety.

The study found that as many as 11 percent of transportation workers work while sleepy, compared to 7 percent of non-transportation workers.

When it came to "sleep dissatisfaction," pilots and train operators took the prize at 50 percent and 57 percent, respectively. They said they rarely or never get decent sleep on nights they work.

The same was true of 44 percent of truck drivers and 42 percent of non-transportation employees. 29 percent of bus, taxi and limo drivers had sleep dissatisfaction.

20 percent of pilots admitted to having committed a "serious error" when flying. Just less than 20 percent of train operators said they experienced a "near miss" due to fatigue, with 14 percent of truck drivers saying the same.

Six percent of pilots and train operators said they have been in car accidents on their way to work. That's compared to just 1 percent of non-transportation workers.