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(CareerBuilder.com) -- Try a couple of things for me: The next time you're in a meeting, yawn -- watch and see how many people follow suit. While you're reading this, count how many times you yawn.

Not because the following information will bore you (at least I hope not) -- keep reading and you'll see why.

The theories surrounding the cause of yawning are abundant. One is that our body stimulates yawns to draw in more oxygen or remove built-up carbon dioxide.

Another is that yawning began with our ancestors, who yawned to show their teeth and intimidate others. A different -- and more common -- conjecture is that we are just plain tired.

Nearly half (46 percent) of Americans feel they are more tired than ever before, according to a new survey conducted by Harris Interactive and commissioned by Diet Pepsi MAX. More importantly, 31 percent blames the workplace as the culprit of their sleepiness.

Check out some findings on sleepiness in the workplace and other fun survey results.

Afternoon slump

Majority (60 percent) of Americans are tired in the afternoon, causing 84 percent to go through an "afternoon slump."

"It's evident that Americans are tired," says Russell Weiner, vice president of Colas, Pepsi-Cola North America. "Most hit a slump at some point in their day, usually while they're at work."

Sixty-six percent of Americans admit to experiencing a slump at least three days a week, while half of those people crash five or more days. The biggest slump occurs between 3 p.m. and 5 p.m., according to the survey, which was also the same time that 23 percent, say they yawn the most.

So what do you do when you feel like you just... (Head nod) can't... (Eyes closing) stay awake? Fifty-two percent of Americans drink a caffeinated beverage while 58 percent walk around the office to get out of their slump.

Asleep on the job

Speaking of nodding off, turns out American's aren't so good at keeping their eyes open in the workplace. A whopping 50 percent of those surveyed say they've caught someone sleeping at work, not to mention the 28 percent who admit they've fallen asleep at work themselves.

Little-known-fact: Auto mechanics (65 percent) have the highest rate of self-admitted snoozing on the job, followed by 51 percent of government workers.

Having trouble staying awake? Follow these pointers from "The Worst-Case Scenario Survival Handbook: Work," by Joshua Piven and David Borgenicht, on how to cover if you're caught sleeping at your desk.

Blame work. Say, "I'm so exhausted; I was here until midnight last night!" Do not attempt this if your boss works late and you do not.

Blame medication. Claim that your new allergy medicine has been making you drowsy. Say, "Those antihistamines just knock me out!"

Blame lunch. Say, "Wow, I guess I should not have eaten that turkey sandwich. Triptophan really makes me sleepy!"

Meetings make me yawn

If turkey sandwiches don't make you sleep, a nice, long, pointless meeting will do the trick.

Fifty-eight percent of all survey respondents have yawned in a meeting and nearly one in five Americans feel embarrassed about it. Washington, D.C. led the nation as the city where people are mostly likely to yawn in a meeting, with 69 percent having done so.

Piven and Borgenicht say warning signs of meeting fatigue include inattentiveness, back tension, shallow breathing, frequent blinking, heavy eyelids and snoring. Follow their tips to stay awake:

Be on guard for mind-numbing repetition. Repetitive noise patterns and repetitive images can cause a trance-like state that deadens the senses. If phrases like "need better communication" and "building a team" are repeated, or if tables, graphs and pie charts are projected endlessly, exit the room for a few minutes.

Wear sunglasses. The harsh glare of fluorescent lights can cause eye strain and lead to fatigue. Wear dark glasses. Use interrogation techniques. Pinch yourself, sit in an uncomfortable position, poke your leg with a pen or paper clip, or stare wide-eyed at a bright-light -- the pain will heighten your awareness.

Crazy yawning facts

Eighty-five percent of Americans don't believe yawning at work should have professional repercussions, while 38 percent of older adults (age 62+) feel it shouldn't happen while on the job.

Fifty-four percent of working Americans say they would take a nap at work if given permission by their supervisor. While more than two-thirds (67 percent) of people living on the West Coast would like to nap at work, 43 percent of those living in the Midwest are opposed to the idea.

Men (36 percent) fall asleep at work twice as much as women (19 percent). Brunettes (19 percent) are more than twice likely as blondes (9 percent) to be teased at work for yawning, even though blondes are more likely to yawn during meetings. E-mail to a friend

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