Elon Musk , the chief executive of Tesla, and Arianna Huffington , co-founder of HuffPost, engaged in a public debate in recent days over how much sleep people need.

In an interview with The New York Times last week, Musk said that the last year had been the most difficult and painful year of my career as he struggled to meet Teslas production targets. He also revealed that he gets very little sleep, working up to 120 hours a week and relying on Ambien when he manages to squeeze in time for rest.