Last weekend, I was talking to a friend in New York who is a top IT manager for an advertising firm. My friend is in the process of remaking the Web presence for a hair-products conglomerate, and his staff is divided among the firm’s offices in New York, Argentina, Singapore and London. On one level, he told me, it’s not a problem: The work can be shared via the Internet, and group conversations can take place on Skype. But here’s the catch: In order to manage people on three other continents, my friend is working at 2 a.m., 5 a.m., noon, 4 p.m. — around the clock. This isn’t “Mad Men,” with time for two-martini lunches, it’s insanity.