Elon Musk: This has been the most painful year of my career

"This past year has been the most difficult and painful year of my career," he said in an emotional interview with The New York Times published late Thursday. "It was excruciating."

The interview -- during which The Times said Musk "alternated between laughter and tears" -- comes amid the turmoil the Tesla chief triggered last week when he tweeted that he had secured funding to take the electric car maker private.

The stunning announcement sent Tesla's stock on a wild ride, prompting lawsuits and reportedly drawing scrutiny from regulators.

Related: Could Elon Musk lose control of Tesla?

Musk told The Times that no one else saw the tweet before he posted it while en route from his house to the airport. He says he doesn't regret sending it and has no plans to leave Twitter.

In a blog post earlier this week, Musk said that the "funding secured" tweet referred to conversations he had with Saudi Arabia's sovereign wealth fund, which left him believing there was "no question" that a deal could be closed.

Musk has argued that taking Tesla private would would relieve the company of the "enormous pressure" of Wall Street's expectations. But there are doubts about whether he will be able to pull the deal off.

The storm set off by his tweet last week follows other difficulties at Tesla and the controversy over another post last month in which he insulted a man who helped rescue a group of Thai boys trapped in a cave.

As Tesla struggled to meet production goals for its Model 3 earlier this year, Musk ended up sleeping at the factory.

Asked if exhaustion was physically affecting him, he told The Times: "It's not been great, actually. I've had friends come by who are really concerned."

He admitted he has had trouble sleeping: "It is often a choice of no sleep or Ambien."

Related: Elon Musk says he expects Saudis to fund plan to take Tesla private

But Musk, who is also the boss of rocket company SpaceX and other ventures, said he has no plans to leave the CEO and chairman roles at Tesla.

"If you have anyone who can do a better job, please let me know," he told The Times. "They can have the job. Is there someone who can do the job better? They can have the reins right now."

Tesla couldn't be reached for comment outside of regular business hours.