This is the remarkably frank exchange Musk had on Twitter over the weekend

"The reality is great highs, terrible lows and unrelenting stress," he revealed.

"Don't think people want to hear about the last two."

Musk was then asked how he dealt with the stress and responded: "I'm sure there are better answers than what I do, which is just take the pain and make sure you really care about what you're doing."

He was then asked if he was bipolar and answered simply: "Yeah."

However, the tech tycoon backtracked a bit and said he was not "medically" affected by mental illness.

"Bad feelings correlate to bad events," he said.