Tesla chief Elon Musk has admitted to The New York Times that stress is taking a heavy toll on him personally in what he calls an "excruciating" year.
The newspaper said the electric car boss alternated between laughter and tears during the interview in which he said he was working up to 120 hours a week and sometimes takes Ambien to get to sleep.
"This past year has been the most difficult and painful year of my career," he said.
"It was excruciating."
The interview published on Friday offered rare insights into Musk's personal life and thinking.
He stands by his tweet last week saying he might take Tesla private and that he had secured the funding to do so.
Asked if he regretted it, he said: "Why would I?"
Musk has a reputation for being an eccentric visionary.
But his out-of-the-blue announcement of a potential $US72 billion ($A99 billion) buyout of the publicly held company raised a huge ruckus and pushed Tesla's shares up 11 per cent in a day.
They have fallen back but remain elevated.
The Wall Street Journal reported that government regulators have subpoenaed Tesla as they dig deeper into his disclosure of the potential buyout.
In the interview with The New York Times, Musk said he fired off the tweet while on his way to the airport.
He said his reference to having secured funding referred to a potential investment by Saudi Arabia's government investment fund.
Musk, 47, said sometimes he did not leave the Tesla factory for three or four days straight and he had not taken off more than a week at a time since he was sick with malaria in 2001.
Musk's social media antics have raised eyebrows as he berated analysts and falsely accused a cave diver of being a pedophile after the man was sceptical about a mini-submarine that Musk sent to possibly help rescue young soccer players from a flooded cave in Thailand.
He later apologised for the remark.
The report cited people familiar with the situation saying Tesla had been trying to find an executive to help relieve some of the pressure on Musk.
Musk said he did not intend to give up his roles as chairman and CEO but if someone could do the job better, "they can have the reins right now".
Australian Associated Press