NEW YORK (Reuters Life!) - Fighting with your spouse can actually be good for your health with people who bottle it all up found to die earlier, a new study shows.

Researchers at the University of Michigan School of Public Health and its Psychology Department released preliminary findings after 17 years of following 192 couples.

The couples fell into four categories: where both partners expressed anger when they felt unfairly attacked, where neither partner expressed their anger, and one category each for where the wife suppressed her feelings and where the husband did so.

"I would say that if you don't express your feelings to your partner and tell them what the problem is when you're unfairly attacked, then you're in trouble," said Ernest Harburg, lead author of the study, in an interview.

The study found that those who kept their anger in were twice as likely to die earlier than those who don't.

There were 13 deaths in the group of 26 pairs where both partners suppressed their emotions, as opposed to only 41 deaths in the remaining 166 pairs.

"When couples get together, one of their main jobs is reconciliation about conflict," Harburg said.

"Usually nobody is trained to do this. If they have good parents, they can imitate, that's fine, but usually the couple is ignorant about the process of resolving conflict."

Harburg said resentment was the real threat -- and suppressing anger led to resentment.

He said it is the resentment that interacts with any medical vulnerabilities a person might have, increasing their chances of succumbing to that medical problem.

"It's healthy to recognize that you're being attacked unfairly and it's even more healthy to speak up and to talk about it and try to resolve the problem if you want to live longer," said Harburg.

(Reporting by Stefanie Kranjec; Editing by Belinda Goldsmith)