Tesla founder Elon Musk has admitted that stress over his business has caused him health problems, and that his myriad executive responsibilities are taking a toll on his personal life. In an interview with the New York Times published on Thursday, Musk said he had been working up to 120 hours a week. “It’s not been great, actually. I’ve had friends come by who are really concerned,” he said.

Speaking about work pressure, Musk said his professional life has been excruciating. “This past year has been the most difficult and painful year of my career,” he told the daily. He cited instances when he had to spend his 47th birthday on June 28 at a Tesla factory and was about to miss his brother’s wedding. Musk said there were times he did not leave the factory for three or four days.

Musk has been mired in controversy ever since he announced on Twitter that he was considering taking Tesla private at $420 (approximately Rs 29,000) a share, and that funding was “secured”. He told employees that as a publicly-listed company, Tesla’s stock price was subject to “wild swings”, which are a distraction for the staff. Tesla’s stock rose by 11% after the tweet.

Investigators in the San Francisco office of the Securities and Exchange Commission asked Tesla for explanations the very next day. Later, two investors sued him and Tesla for allegedly manipulating the company’s share prices through false and misleading tweets.

The figure $420 is a code for marijuana in counterculture lore. “It seemed like better karma at $420 than at $419,” Musk said. “But I was not on weed, to be clear. Weed is not helpful for productivity. There’s a reason for the word ‘stoned.’ You just sit there like a stone on weed.”

He blamed short-sellers — investors who bet that Tesla’s shares will lose value — for his stress. “I thought the worst of it was over,” he told the New York Times. “But from a personal standpoint, the worst is yet to come.” He said he was bracing for “a few months of extreme torture from the short-sellers, who are desperately pushing a narrative that will possibly result in Tesla’s destruction.”

Asked about rumours of appointing a second-in-command in Tesla, Musk said he had no plans to give up his dual roles of chairperson and chief executive. “[But] if you have anyone who can do a better job, please let me know,” he said. “They can have the job. Is there someone who can do the job better? They can have the reins right now.”