LAS VEGAS: McDonald's Restaurants' US outlets may soon open as early as 5am as the company seeks to respond to Americans' changing eating habits.

Some 75% of the chain's restaurants currently open at that time, said executives at a conference for McDonald's 16,000 managers.

They revealed that the breakfast period now begins earlier than previously, in part because of the times that customers now commute to work.

Janice Fields, chief operating officer for McDonald's USA, said: "I'm amazed at the people who work for me who take their kids to hockey at 4am and 5am. I want us to be open when they need us."

The move marks a new effort by the company to increase sales in an area with high growth potential; and also to counter the activity of rivals like Starbuck's, Wendy's and Burger King, all of which are increasing their breakfast offerings.

Data sourced from Wall Street Journal Online. additional content by WARC staff