Electric car maker Tesla's CEO Elon Musk has admitted in a wide-ranging interview with The New York Times that stress is taking a heavy toll in what he calls an "excruciating year."
In the newspaper's account of the interview, published Friday, Musk said he was working up to 120 hours a week and sometimes takes Ambien to get to sleep.
Musk stood by his tweet last week saying he might take Tesla private.
Reports say government regulators have subpoenaed Tesla as they dig deeper into his disclosure of the potential buyout.
The subpoena signals regulators are investigating if Musk was telling the truth in his tweet about have financing locked up for a deal that analysts have estimated would require $25 billion to $50 billion.