People's reactions to the 9/11 attacks were recorded
People who do not talk about traumatic experiences can fare better than those who "let it all out", say researchers.
The University at Buffalo study compared the progress of 3,000 people who took different approaches over two years following the 9/11 attacks.
It found people initially unwilling to talk were less likely to be adversely affected two years later.
But a UK psychologist said that other studies had suggested that for many people talking did help.
The popular advice that it is better to talk about your feelings after a trauma has been the subject of dozens of different research projects.
This latest one involved 3,000 people who completed online surveys in the days immediately following the 2001 attacks and over the course of the next two years.
Those taking part had not lost a loved one or friend.
People who took part were allocated to different groups depending on whether they said that they felt ready to express their feelings or not.
If the assumption that it is healthier to talk about feelings is correct, then the researchers, led by Dr Mark Seery, would expect to see those who were initially uncommunicative coping worse over time with their traumatic memories.
However, the reverse was true, and those who chose not to talk appeared to be in better psychological shape.
Dr Seery, whose work was published in the Journal of Consulting and Clinical Psychology, said: "We should be telling people there is likely nothing wrong if they do not want to express their thoughts and feelings after experiencing a collective trauma.
"In fact, they can cope quite successfully and, according to our results, are likely to be better off than someone who does want to express his or her feelings."
Professor Stephen Joseph, who specialises in trauma following disasters, said that it was important not to generalise about the "right" approach for all patients.
He said that other studies had suggested that for many people, talking about their experiences with the support of proper counselling, was the correct road to recovery.
He said: "Those people who wanted to express their feelings immediately after 9/11 may have been those who were most deeply affected by it, so it is not entirely unsurprising that they may still have symptoms two years later."