Researchers have chronicled five major personality changes that newlywed couples go through in the first year of marriage.

A study led by psychologist Justin Lavner at the University of Georgia has found that personality changes in newlywed couples occur early during the course of marriage and the transformation happens regardless of age, demographics and the duration of relationship prior to marriage.

The findings showed that the biggest personality changes were related to the couples' openness, conscientiousness, extraversion, agreeableness and neuroticism, according to the Daily Mail.

A total of 169 heterosexual newlywed couples were asked questions focused on measuring the levels of the Big Five personality traits.

The research, which was published recently in Developmental Psychology, suggested that both the husband and the wife will often become less agreeable during the first year of marriage.

During the early months, the men will become less extroverted, while the women will be less open, the study indicated.

The findings also showed that wives will become less neurotic and husbands will become more conscientious and emotionally stable during the first year.

"These results did not differ by spouses' age, demographics, relationship length prior to marriage, cohabitation prior to marriage, initial marital satisfaction, or parenthood status," the research stated.

"Initial levels of personality as well as changes in personality over time were associated with spouses' marital satisfaction trajectories. Taken together, these findings indicate that newlywed spouses' personalities undergo meaningful changes during the newlywed years and these changes are associated with changes in spouses' marital satisfaction," it continued.

Meawhile, another study conducted by researchers from Pennsylvania State and Brigham Young Univesrity has claimed that married couples who have been together for 20 years are happier than newlyweds.

The findings were based on data from the Marital Instability Over the Life Course study, which focused on the rise and decline of marital satisfaction of 2,034 married couples.

The researchers noted that there is a drop in marital satisfaction among the participating couples during the first 20 years of marriage, but there was stability in the satisfaction levels after this period.

The authors of the study said that the findings reveal how couples find "deeper levels of appreciation" after being together for a long period of time, which they say leads to greater marital satisfaction.

Harry Benson, research director at the Marriage Foundation, dismissed the idea that married couples start to dislike each other after being together for so long.

"It's a depressing and misleading stereotype that sitcoms like to portray, and until now researchers have generally agreed that marriages start well but thereafter drift into terminal decline. Only it's a complete myth." he said, according to The Times.