It's eight years since the 9/11 attacks. The trauma of such an event can affect the lives of survivors for years. And also the relatives of those who died on that day.
But post-traumatic stress disorder (PTSD) is not limited only to those who experience such large-scale devastation, wars and natural disasters.
Car accidents, muggings and assaults can have exactly the same effect on people. PTSD is an under-recognised mood disorder. In fact, during World War 1, people were unaware of its existence, and the British army shot dead many of their own soldiers who could not continue fighting because of their mental state.
Find out everything you need to know about PTSD, its symptoms, causes and treatment.
(Health24, September 2009)