Most drivers know what it's like to be caught in heavy traffic and suddenly feel the beginnings of droopy eyelids or a stifled yawn. But many on the roads are probably unaware of just how prevalent this feeling is - and how dangerous it can be.
The Centers for Disease Control and Prevention (CDC) recently released a study revealing that about 4 percent of adults admitted to falling asleep behind the wheel in the previous month, CBS Local reports. These numbers don't even include teenage drivers or people from the 31 states not included in the survey, which means the actual number could be much higher.
Another study by AAA found that young drivers ages 16 to 24 are more likely to ignore their sleepiness and get behind the wheel, even if they aren't cognitively alert enough to do so. More than 30 percent of surveyed people in this age group admit to driving while struggling to keep their eyes open.
The sheer number of drowsy drivers on the roads leads to a large number of crashes. According to AutoBlog, tired drivers accounted for more than 30,000 car accidents in 2009, with many of these crashes ending with injuries, a large amount of necessary car repair and even death.