Some people enjoy working like that, and enjoy their jobs enough that they don't care that they're actually working. The extreme example is John Carmack, who a

Some people enjoy working like that, and enjoy their jobs enough that they don't care that they're actually working. The extreme example is John Carmack, who according to the book "The Masters of Doom", would crank music all night, and drink diet pepsi (early days of id, grant you, I don't know how he works now) while programming. He rolled in the office at 4pm and stayed until early morning. There's nothing wrong with working crazy late hours if you enjoy it.