Nerve-racking vs nerve-wracking

The Common Sense Journalism blog offers some insight on deciding between using "nerve-racking" or "nerve-wracking." The AP Style Book has always been a bit unclear on the difference between the two and when looking at the definitions of the words rack and wrack, the difference is still hard to notice. "Rack" in the AP Style Book is defined as torment: He was placed on the rack. She racked her brain.From this one could draw the conclusion that nerve-racked person is being tortured by their nerves. The wire service has recently released a clarification, however. "The noun wrack means ruin or destruction, and generally is confined to the phrase wrack and ruin and wracked with doubt (or pain). Also, nerve-wracking." So now you have to decide which definition you feel is the most accurate in context to what you are writing.