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Vasovagal syncope caused meteorologist's on-air collapse. Here's what to know about it.

Meteorologist reacts to fainting on live TV
KCAL-TV meteorologist Alissa Carlson describes what happened before she fainted on live TV 05:13

CBS Los Angeles viewers witnessed a scary moment over the weekend when KCAL News meteorologist Alissa Carlson fainted live on air Saturday, just as she was about to deliver a weather forecast.

Now fully recovered and with some answers about what happened, Carlson joined "CBS Mornings" to share how she's doing and what doctors say caused the sudden collapse: a condition called vasovagal syncope.

Carlson said she had started out that morning feeling fine.

"It wasn't really until 15 minutes prior to the incident that I started to feel a little nausea," Carlson recounted. She noted she hadn't eaten breakfast and was drinking a lot of coffee, "and so most likely I was maybe a little dehydrated."

CBS News chief medical correspondent Dr. Jon LaPook, who also joined to discuss, explained that "syncope" means blacking out, "vaso" means blood vessel and "vagal" refers to the vagus nerve.

"If the vagus nerve is overstimulated or inappropriately stimulated, the pulse rate can go down, the blood pressure goes down, not enough blood goes up to the head and you can faint," LaPook explained.

In addition to nausea, other symptoms of vasovagal syncope include going pale, lightheadedness, feeling warm and blurry vision.

There are also often warning signs to look out for, LaPook said, including:

  • sweaty palms
  • tunnel vision
  • graying out vision
  • dizziness

"People, like especially in this situation, you're embarrassed. 'I'm going to sit up and look normal.' That's the worst thing you can do," LaPook warned. "You want to get flat so your heart is at the same level as your head."

He suggests laying flat on your back, bringing your legs up if you can and turning your head to the side in case you vomit.

Despite previously being diagnosed with a leaky heart valve, Carlson, who is also a health coach, was happy to report the fainting was not linked to a heart attack.

"That was not the case, thankfully, and heart tests prove I'm fine, my heart is great," she said, adding she now just needs to be on the lookout for signs of her newly diagnosed condition. 

"I continue to strive for ultimate health," she said, and offered some words of advice to others: "Get enough rest, make sure you're hydrated, and take care of yourself."

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