Telsa board members are concerned about Elon Musk's use of Ambien and recreational drugs, according to an explosive interview with The New York Times published late Thursday.

Musk said in the interview he now needs Ambien to sleep, but board members are concerned that the drug isn't having the intended effect for Musk, the Times reported citing an unnamed source. Instead they fear it's fueling his controversial public statements. The report also says board members are aware that Musk has used unspecified "recreational drugs."

Ambien maker Sanofi warns against taking the sleeping aid unless you intend to stay in bed for a full seven to eight hours.

The report comes amid speculation about drug use around Musk's market-moving tweet about taking the company private. It's just the latest in a series of controversial tweets from Musk, who recently called a diver involved in the Thai cave rescue a pedophile and lashed out at journalists for what he said was unfair coverage. Musk later apologized to the Thai diver and separately for what he called bad manners.

The Aug. 7 tweet sent Tesla shares seesawing and company directors scrambling to do damage control — and at the same time spurred jokes and questions about whether Musk's proposed $420 price tag was inspired by drug use. The number 420 is commonly associated with marijuana.

"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," Musk said in the interview.

Musk said he arrived at the price tag by calculating an approximate 20 percent upside from current stock levels and then rounding up one dollar: "It seemed like better karma at $420 than at $419."

Tesla provided a statement to the Times in response to questions for the article that it attributed to its board, excluding Elon Musk. The statement said, in part, that "We would like to make clear that Elon's commitment and dedication to Tesla is obvious."