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ABC News' Andrea Canning Reports:

Fainting, it happens to 60 percent of all Americans at some point,  and it has stricken many when the cameras rolled  and the stage lights shined the brightest.

Akshay Buddiga hit the floor during the National Spelling Bee in 2004,  Marie Osmond collapsed on Dancing with the Stars in 2007 and American Idol's Symone Black fell off the stage during this season's auditions.

"People faint when there's a decreased blood flow to the brain," Dr. Lawrence Phillips, an assistant professor of medicine at NYU Langone Medical Center, told ABC News. "It kind of occurs temporarily, and then they pass out and then the blood flow restores to the brain, which causes them to wake up."

It is an occurrence so common  that few seek medical attention.

"Everyone doesn't have to be alarmed that there is a serious medical problem if they pass out. But it is important for the first time you pass out that you do have further evaluation," Phillips said. "It's important to try to  get to the bottom of why people are fainting."

Click here for a checklist of questions to ask your doctor when diagnosing fainting.

Kristine Breese thought her occasional fainting was no big deal, but now the 47-year-old mother of two and marathon runner is speaking out as part of an international public awareness campaign to get more people to pay attention to what fainting can signal.

Experts say that 25 percent of the time, fainting can indicate a potentially deadly heart condition, a condition Breese had for years before it was finally diagnosed after she passed out at home in the presence of her sister-in- law.

"My skin was gray, and I was shaking. … She was telling me that she had called 911. I said something like 'I can't go to the hospital; I've got to cook dinner,'" Breese told ABC News.

Instead, she was rushed to the hospital, where doctors referred her to specialists. While they were running tests,  Breese went into cardiac arrest.

"My heart actually stopped, and the doctor had to resuscitate me," she said.

Breese was diagnosed with cardiogenic syncope, or an irregular heartbeat.

"The great news was that they knew exactly what to do and that would be for me to get a pacemaker," Breese  said. "I didn't think I could be someone with a heart condition. … What I learned through this whole experience [was] to take symptoms seriously and to take myself seriously."