Fortunately, research suggests that most people will not develop PTSD in response to September 11. Studies show that the severity and duration of an individual's exposure to a traumatic event strongly influence the likelihood of developing PTSD. Consequently, people closest to it -- those in the World Trade Center when the planes hit, for instance, or those who witnessed people jumping from windows -- are more susceptible than are the majority of Americans who watched the tragedy on television.

For those who develop PTSD, symptoms most likely appear within a few days of the traumatic event. Friedman emphasizes, however, that symptoms can take months and sometimes years to surface. Even so, experts now assert that the original prediction of a PTSD epidemic after September 11 was premature and that most of us should expect normal and full recovery to take place. They also stress that experiencing symptoms of stress, anxiety and depression is a fairly predictable, well-understood response to a catastrophic event. But that doesn't imply we should ignore symptoms if they arise and linger.

"New York City has been inspirational in so many ways to people in the rest of the country," Wyle says. "But if I was going to speak to anybody here about PTSD, I'd say, 'Really check in with yourself.' If you're having trouble sleeping, if images are invading your life, if you find yourself becoming desensitized, then definitely seek out medical help. The city seems to be coping very well, but that doesn't mean we should forget that there are a lot of people suffering that need not be."

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