Sherman, an inveterate insomniac, was generally alert to the slightest shift in wakefulness, signaling that he was finally, finally going under. But last night Sherman missed a sure sign — the sense that music was pouring through his toes. What he does remember was endlessly reviewing the minutia of his stock holdings, revisiting the regrets, like selling off Facebook right before it hit bottom. The stray remark overheard in the lobby of his building about the value of Twitter going public. Sleep evaded him. The sheets were first too cold and clean and then too old and dirty. He shifted, he turned, haunted by the sense of the misplaced thought. A forgotten birthday? A girlfriend from back in the day? An unpaid bill? Or maybe a recipe that was sure to impress his latest conquest — a recipe that never existed in the first place.