Daniel Lubetzky says his days of choosing work over sleep are long gone, and he's more productive because of it.

Lubetzky, the billionaire Kind Snacks founder and newest permanent investor judge on ABC's "Shark Tank," was once a major night owl — perhaps involuntarily, he says. He couldn't relax without clearing his inbox, leading to countless all-nighters: While his family was sound asleep, he responded to messages.

"I have a little bit of an obsessive personality," Lubetzky, 56, tells CNBC Make It. "If I had emails in my inbox [waiting to be] read, I couldn't take it. I was enslaved by my inbox. So after my kids and wife went to bed at 10 or 11 at night, I would start checking all my emails. Sometimes, I finished at 2, 3, 4 a.m."

His work ethic helped Kind double its annual sales for more than 10 years in a row, he told Inc. in 2018. But he loved the feeling of being busy so much that he didn't realize he wasn't taking care of himself, he now says: His many years of only getting four hours of rest every day caused "severe, chronic sleep deprivation."

Since the Covid-19 pandemic's onset, Lubetzky has tried to live more healthily, he says. He attempts to get into bed "at a good time," which he defines as roughly 12:30 a.m. His goal: Go to sleep and wake up at the same time every day, no matter how many emails are left unread.

"That's helped me get better quality sleep," Lubetzky says. He has more time for workouts, he adds, and he's more focused and clear-headed at work: "It's made a huge difference for me and helps me be more productive."

About one in three adults in the United States don't get enough sleep every day, according to the Centers for Disease Control and Prevention. Most adults need at least seven hours of sleep per night, says the CDC. Chronic sleep deprivation can lead to heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity and depression, adds the National Institutes of Health.

Lubetzky joins the likes of fellow billionaires like Elon Musk and Bill Gates, who once sacrificed sleep to get things done. "I've tried [to sleep] less, but ... even though I'm awake more hours, I get less done," Musk told CNBC last year. "And the brain pain level is bad if I get less than six hours [of sleep per night]."

Gates' all-nighters took a "big toll" on him, he wrote in a 2019 blog post. Now, he works to get at least seven hours of sleep per night, he noted.

Lubetzky can tell the difference in his health simply by comparing new and old photos of himself, he says.

"If you look at pictures of me from 10,15 years ago, I look 10 or 20 years older," says Lubetzky. "I'm all pudgy and all pale and all because I was sleeping four hours a day ... But I am developing much better habits to take care of myself."

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."

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