BHP CEO Andrew Mackenzie told Qantas' latest inflight magazine that he arrived at work "quite late by modern standards and I leave quite early" because he knew he would work in the evening for the global company.
"And I've found the more senior I've become, the more important it is that I work fewer hours," Mackenzie said.
"A rested Andrew can do more in four hours than a tired Andrew can do in eight."
Mackenzie was appointed to the top job in May 2013 and his tenure has included the Samarco tailings dam collapse in Brazil and more recently calls for structural change from activist investor Elliott Management.
Recently-appointed BHP chairman Ken MacKenzie has been quick to address reports that Mackenzie's job was on the line, talking up the CEO's achievements at the company's AGM in London this month.
The company met production and unit cost guidance in the September quarter and Mackenzie said at the time BHP was on track to deliver 7% volume growth in the 2018 financial year.