Marriage could provide the answer to long-term happiness and life satisfaction.
Shawn Grover and John Helliwell conducted the study using information sourced from the British Household Panel Survey, which collected data between 1991 and 2009 from around 30,000 people.
They also used the 2011–2013 United Kingdom's Annual Population Survey, which collected information from around 328,000 people.
Their findings were published in the Journal of Happiness Studies.
Previous studies have shown that being married, and living as if married, is associated with higher life satisfaction levels than being single, divorced, separated, or widowed.
Other research has indicated that while this rise in life satisfaction continues for the first few years of marriage, it "eventually falls back to pre-marriage levels."
Grover and Helliwell's new study aimed to determine the effects of married life on well-being and evaluate their permanence. Furthermore, the researchers wanted to delve deeper into the source of the impact of marriage on well-being and explore the role of friendship in marriage.
Echoing the findings of previous studies, the researchers found that married couples reported the highest levels of life satisfaction, with similar levels for people living as couples. Couples remained more satisfied with life from the early stages of marriage through to old age.
"Even after years, the married are still more satisfied," comments Helliwell. "This suggests a causal effect at all stages of the marriage, from pre-nuptial bliss to marriages of long-duration."
Benefits are 'unlikely to be short-lived'
Next, the team wanted to examine the different stages following marriage and age to test whether the enhancement in well-being that comes with marriage is temporary.
The scientists hypothesized that if the benefits to well-being from being married are fleeting, then they would expect the differences between married and unmarried people to be greatest at ages when more people typically marry and smaller at ages when fewer people get married.
On average, couples in the U.K. marry at around age 30.8 for men and age 28.8 for women. Therefore, the scientists expected to see the differences between married and unmarried people to be greatest in the 20s and 30s. However, this was not the case.
Other studies have demonstrated that there is a U-shape correlation between life satisfaction and age. Life satisfaction is high before the age of 25, dips during mid-life, and then rises back up through the later years of life.
Although the same mid-life dip in life satisfaction was observed among married and single people, the slump was more significant among unmarried people.
"Marriage may help ease the causes of a mid-life dip in life satisfaction," explains Helliwell, "and the benefits of marriage are unlikely to be short-lived."
Benefits of marriage higher for best friends
Marriage and friendship are both linked to life satisfaction. The team aimed to assess whether there are interactions between marriage and friendship in achieving life satisfaction.
The research team noted that if friendship explains most of the benefits to well-being in marriage, then life satisfaction should be higher among those who list their spouse as a close friend. About half of married and cohabiting couples reported their partner as their best friend.
Being married or living with your best friend was shown to boost the benefits to well-being even further and were more pronounced for women than men.
"The well-being benefits of marriage are much greater for those who also regard their spouse as their best friend. These benefits are on average about twice as large for people whose spouse is also their best friend."
The authors conclude by saying that although all friends play an important role in happiness, those who are married or share beliefs are "super-friends," with the increased effect on well-being being much more substantial, on average, than for friends alone.