Robert Downey Jr. claims coffee has saved his sanity.

The 'Oppenheimer' actor can't start the day without his favourite hot caffeinated beverage - which he takes black - and his wife Susan Downey has learned not to try and discuss anything important with him until he's downed his morning drink.

He told People magazine: "[Every morning] I roll out of bed, I hit my knees. I have one of several prayers, usually of gratitude or just being like, ‘Please let me stay out of my way.’ And then I roll downstairs for coffee. I credit coffee, in part, for my sanity.

“When we have some big day ahead of us, [Susan is] like, ‘Wait, wait, wait, don’t talk to him yet.' And she’ll bring me a cup.”

And the 58-year-old star - who has Indio, 30, with first wife Deborah Falconer and Exton, 11, and Avri, nine, with Susan - credits his childhood for his love of coffee.

He said: "To me, it is family. It is home. I associate that morning coffee with my mom, getting ready to drive me to school. You want to talk about ‘mother's little helper’ back in the '60s and '70s, it's the unsung hero of proper parenting.”

Robert has teamed up with entrepreneur Craig Dubitsky to launch his own coffee company, HAPPY, which includes whole beans, ground, instant coffee and K-cup-compatible pods and it was important for the pair not to be "snobby" about their creation.

The 'Iron Man' star said: “It's just become such a massive industry, but we realised you're either getting stuff that tastes like pencil shavings, or you're getting the [artisanal] stuff that was passed through the small intestine of a yak...

“Honestly, I love it so much that I'm agnostic about whether it's low-end stuff that you're getting at a truck stop or now these almost comically complicated and highfalutin blends.

"I don't want to overcomplicate this. I want to feel like I'm making coffee that ticks all the boxes for everybody.”

Craig added: "We didn't want to be, we made up this word, baristacrats. We didn't want to be snobby.

“It was important for us to make something that could elevate the every day.”

The pair have teamed up with the National Alliance on Mental Illness (NAMI) and their coffee packaging includes information on how to find assistance.

Craig said: “Coffee sparks conversation. And loneliness is another big, big epidemic in this country. In some ways, we're not in the coffee business, we're in the happy business. That said, we're still making sure the coffee is awesome.”