It is a proven fact that marriage is good for both mind and body.
One of the first studies to show this was by Dr William Farr, a British epidemiologist who set out to study in 1858 what he called the "conjugal condition" of the people of France.
Using birth, death and marriage records, he divided the adult population into three categories - the married, consisting of husbands and wives; the celibate, defined as bachelors and spinsters who never married; and, finally, the widowed, those who had experienced the death of a spouse - and analysed the mortality rates of the three groups.
His work showed that those who are single died from disease "in undue proportion" to their married counterparts. And the widowed, Dr Farr found, fared worst of all.
His study was one of the first to expound the "marriage advantage", the fact that married people, on average, appear to be healthier and live longer than unmarried people, said Ms Andrea Chan, a counsellor at the Centre for Effective Living at Camden Medical Centre, which provides counselling services.
More recent research bears out Dr Farr's findings.
The Framingham Offspring Study, for instance, evaluated 3,682 adults in the United States from 1984 to 1987. Measures of marital status, marital strain and risk factors for coronary heart disease were collected at the baseline examination.
The 10-year follow-up for incidence of coronary heart disease and total mortality found that married men had a 46 per cent lower rate of death than unmarried men. This was after taking into account major heart risk factors such as age, body fat, smoking, blood pressure, diabetes and cholesterol level.
It is part of the Framingham Heart Study, which is a long-term, ongoing cardiovascular study on residents of the town of Framingham, Massachusetts. The study by the National Heart, Lung and Blood Institute and Boston University began in 1948 with 5,209 adults, and is now on its third generation of participants.
Though Valentine's Day today will be all about romantic love, it seems it is the sturdiness and balance of married love, however unromantic, that should be celebrated.
Marriage has been shown to confer benefits associated with longevity, better physical health, less risk of engaging in risky health behaviour, better mental health and reduced risk of depression and anxiety disorders, said Ms Chan.
Married women have lower levels of depression, and those with bipolar disorder - characterised by periods of prolonged and excessively elevated or irritable moods alternating with periods of deep depression - have fewer and milder depressive episodes.
Strong support network
There are some theories as to why marriage is good for health.
Couples in a stable relationship have good social and psychological support and can encourage each other to lead healthy lifestyles.
The support network from a strong marital relationship - and the wider family relationships gained because of marriage - provides help and resources in times of stress, said Ms Chan.
Marriage offers protection against the risks of being alone.
"With marriage, you can have someone to look out for you when you are ill, look after you in times of sickness, or simply have someone to share and discuss concerns and problems with," said Ms Chan.
Researchers have found that emotional support from a spouse can help people recover from both minor and major illnesses and even help cope with chronic diseases.
Also, married couples have a vested interest in watching out for each other and encouraging healthy choices and behaviour.
Wives tend to be a more positive influence on their husbands and are more likely to remind them to refrain from drinking or smoking, said Dr Liu Hui, an assistant professor of sociology at Michigan State University.
Men actually decrease many self-destructive patterns before their wedding date, said Ms Chan.
Another possible basis for the health benefits of marriage is self-selection - the theory that healthy people get married and stay married, and people who are of poorer health either do not marry or are more likely to become separated, divorced or widowed.
Overall, this association between marital status and health persists regardless of socio-economic status, education and poverty, where people were born or their ethnicity.
However, marriage is only as good as it is happy.
Studies show that singles are happier and in better health than divorced or widowed people, said Ms Chan.
For more than 100 years, scientists have speculated that single people have poorer health than those who are married, because singles generally have fewer resources, less income and perhaps less logistical and emotional support.
But a study by the University of Miami of 143,063 men with prostate cancer found that men who had divorced or been widowed had worse health problems than men who had been single their entire lives.
Over a 17-year period (1973 to 1990), the median survival of married men was 69 months, compared with 49 months for men who had never married. Worst off were the separated and widowed patients, whose median survival was 38 months.
In 2011, The Journal Of Health And Social Behaviour published a study tracking the marital history and health of nearly 9,000 men and women in their 50s and 60s.
In the study, researchers at the University of Chicago found that when the married people became single again - either by divorce or because of the death of a spouse - they suffered a decline in physical health from which they never fully recovered.
These men and women had 20 per cent more chronic health issues, such as heart disease and diabetes, than those who were still married to their first husband or wife by middle age.
The divorced and widowed also aged less gracefully, reporting more problems going up and down stairs or walking longer distances.
Interestingly, research also suggests that the health benefits enjoyed by married people may not exist in other types of intimate relationships.
Several studies have found that cohabiting couples do not share the mechanisms resulting in the increased likelihood of longevity and health.
Unlike marriage, cohabitation is negatively associated with both financial satisfaction and health, said Ms Chan.
Several researchers have noted that cohabiters have poorer psychological well-being compared with married individuals, "suggesting that the protection effects of marriage are not applicable to cohabitation".
This could be because society is not set up to confer the same social, legal and financial benefits to couples who are not married.
However, happy marriages do not happen by accident, said Mr Benny Bong, a family and marital therapist and the director of private counselling agency, The Family Therapist.
"It begins with making a well thought-through choice of partner, to adequately preparing oneself for this journey and practising a whole range of skills throughout the marriage to tweak it to perfection," he said.
When couples are able to work successfully at this central relationship of their lives, they will tap a source that feeds the deepest needs of being human.
Mr Bong said: "It would seem that we are not meant to be solitary creatures and even the most independent of us occasionally long for the company of another.
"And when we are in a mutually loving relationship, we feel wanted and valued as a person."
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