(USAToday) - At 4 o'clock in the morning, Shafer Vineyards is alive with light and motion. The sun won't be up for more than three hours, but lines of pickers are moving methodically down vines full of ripe cabernet sauvignon grapes. They're lit by huge bright lights mounted on tractors trundling alongside. The scene at this vineyard is part of a worldwide practice that's increasingly the way all wine grapes are harvested — in the dead of night. It results in better wine, lower energy costs and happier workers.