Researchers at Carneige Mellon University studied married couples and found that intimate relationships can affect a person's health.

Biological evidence explains married couple is happier than singles

Researchers took saliva samples for cortisol test from 572 adults between 21 and 55 years old. In order to analyze the cortisol, the experts recorded each individual's cortisol daily rhythm.

Why cortisol?

Cortisol is 'the stress detector' in our body. Generally, the cortisol level increases when a person wakes up and then it declines during the day.

When a person is stressed, the cortisol levels peak and regulate inflammation. This can promote the risks of getting diseases, Futurity wrote.

What's the result?

The evidence proved that married couples had lower cortisol levels than of those who never married and those that are divorced. The paper explained how cortisol levels in married couples declined faster - a sign associated with a lower risk of heart disease.

An ideal #marriage is a true partnership between two imperfect people, each striving to complement the other.

— Marriage Solved (@MarriageSolved) February 5, 2017

Other evidences

In a separate study conducted in the UK, researchers found that married couples get the support they need for each other to raise kids or when work is under pressure, Daily Mail reported. Furthermore, the study noted that those who think that their spouse is their best friend, have the highest rate of happiness.

Another survey in Finland has also found that 90 percent of married couples have a happy relationship because they feel loved and appreciated.

What researchers want you to know?

According to Pew Research Center, 88 percent Americans think that love is the very first reason why people get married. Albeit not trying to point out that being married is better than being singles, the biological evidence has proven that a relationship can affect one's health condition.