sleep

In June 2011, after the sixth game of the Stanley Cup Finals between the Vancouver Canucks and the Boston Bruins, in Boston, the series was locked in a tie. The Canucks, based in the Pacific Time Zone, had lost all the games hosted in Boston. The Bruins, located in the Eastern Time Zone, had fallen in every contest hosted in Vancouver. As the team with the better regular-season record, the Canucks held home-ice advantage for the seventh and deciding game. So when the Bruins arrived in Vancouver the day before that matchup, they went searching for an edge.

“I was getting ready to take the stage for a lecture in Minnesota when my phone rings,” says Charles A. Czeisler, Ph.D., M.D., sitting in a small, windowless conference room outside his office at the Brigham and Women’s Hospital at Harvard Medical School in Boston, where he serves as the chief of the Division of Sleep Medicine. “It’s the Bruins’ team physician, who says, ‘I’m here in Vancouver, and I’m wondering if you have any suggestions for what we might do.’”

Czeisler asked a number of questions about the Bruins’ travel schedule. He discovered that the team planned to take their discipline of napping in the afternoon with them to Vancouver the next day. “I told him that that doesn’t work—the team needs to be napping in the morning in Vancouver, because that is afternoon here in Boston.” In other words, to maximise their energy and mood, the players should keep their bodies on Eastern Time. “There is a circadian rhythm to athletic performance,” he says, referring to the study of the human body’s inner clockwork.

Physiologically, the window for peak focus, strength, reaction time, and physical flexibility arrives in late afternoon or early evening, when “the body is sending out its strongest drive for wakefulness,” says Czeisler. According to him,