Media mogul Arianna Huffington has been very vocal about the importance of sleep since accidentally overworking herself to the point of exhaustion in 2007.

Critics may point out that she managed to establish a successful media company, the Huffington Post, after years of losing sleep and prior to becoming a champion for wellness and balance. But Huffington says that's not the case.

Contrary to popular belief, she tells CNBC Make It at a Fuel List event hosted by her wellness site Thrive Global, that she truly became successful when she quit working round-the-clock.

"I have to assure you that the success at the Huffington Post happened after I started taking care of myself," says Huffington.

In 2007, Huffington was making phone calls and checking her email when she passed out at her desk. She awoke in a pool of blood with her daughter standing above her.

"Huffington Post was only a two-year-old baby when I collapsed," says Huffington, noting that the company had not yet achieved the influence and readership that it has today.

After coming to realize the importance of sleep, Huffington started to see a difference in her work style and that's when, she says, her business began to grow.

"I can tell you with authority that when I'm exhausted, when I'm running on empty, I'm the worst version of myself," says the entrepreneur. "I'm more reactive. I'm less empathetic. I'm less creative. And all of us can testify to that."