PHILADELPHIA—A study published Monday in the Annals Of Internal Medicine concludes that the average American needs at least six full hours of uninterrupted sleep at work in order to leave the office feeling refreshed and alert. "Millions of people are staying up way too late at work," said endocrinologist Hannah Presnall, adding that in order for the body to function properly, workers should arrive at their job, check and send e-mails for two to three hours, and be asleep by 11:30 a.m. at the latest. "More and more people are pulling all-dayers and drinking coffee just to keep themselves awake for meetings and conference calls. But when compared with their better-rested coworkers, these individuals are far more likely to suffer from fatigue and decreased cognitive performance at home." The study recommends that adults who continually find themselves awake at work take Ambien first thing in the morning so they can fall asleep as soon as they arrive at the office.