Loneliness: the next big global health problem?

It is predicted that loneliness could reach epidemic proportions by 2030 – and it is very bad for your health

Take the case of a young man or woman who is a modest smoker, obese, takes no exercise and has no friends. What is the single most effective step that he or she can take to improve health prospects? The answer is to make a few friends.

This surprising conclusion is drawn by Julianne Holt-Lunstad, of Brigham Young University, based on considerable research. Her most recent paper, a meta-analysis of loneliness and social isolation as risk factors for mortality, was published in Perspectives on Psychological Science.

Several lifestyle and environmental factors are risk factors for early mortality, for example smoking and a sedentary lifestyle, but social factors known to have equivalent influences on mortality risks get much less attention. There is very good evidence that having meaningful close relationships and diverse social connections boosts our immune system, reduces general stress and cardiovascular stress, and supports and improves mental health.

On the other hand, loneliness and poor social support have very negative effects. Holt-Lunstad’s research shows that feelings of loneliness increase risk of death by 26 per cent, lack of social connections increases risk of death by 29 per cent and living alone increases risk of death by 32 per cent.


Loneliness could well be the next big public health issue. Several decades ago scientists studying dietary habits predicted that an epidemic of obesity was coming. That epidemic has arrived.

On the other hand, we hear little or nothing today about the corrosive effects of loneliness or social isolation on health. Holt-Lunstad likens the current status of research in this area to that of research on obesity 30 years ago.

Loneliness and social isolation are increasing sharply worldwide, particularly in more affluent countries and particularly among adult males. The numbers of Americans who say they have no close friends has increased threefold in recent decades (General Social Survey). It is predicted that loneliness will reach epidemic proportions by 2030 unless preventive action is taken.

Five close friends needed

People now have many social media “friends” but these do not compensate for real friends one meets face to face, with whom one laughs, laments and complains and confides in, and so on. It is estimated that you need three to five close friends in order to derive the optimal health benefit, but even one good friend can have a big effect. Kin – brother, sister, spouse and so on – while effective, are not as powerful as non-kin friends.

There is, of course, a limit to the number of people with whom the human brain can maintain a close connection, called Dunbar's Number, after Oxford University evolutionary psychologist Robin Dunbar, who has extensively studied the primate brain and social circles.

The brain’s neocortex (that part added on in mammals to the small reptilian brain) capacity limits the size of the circle of social contacts you can maintain to about 150 people – about the size of the group you would invite to a large party. Within that group, your 15 closest relationships are the most important when it comes to boosting your mental and physical health.

Social media and texting now make it easy for us to have many contacts at a distance, and we tend to substitute these remote contacts for real friendships, which only develop when people meet frequently face to face and confide in each other. Other modern practices that work against making close personal friendships are watching too much TV, surfing the internet, constantly prodding smartphones and tablets, video games, frantic social schedules and so on. Closing post offices and the new drink-driving regulations mitigate against older people maintaining easy social contacts in rural areas. Divorce rates are rising, and recent research shows that divorce causes increased loneliness and diminished life satisfaction among adolescent children of divorced parents.

Finally, it is important to remember that if you want to have a friend, you must be a friend. Friendship should be pursued and cultivated for its own sake and not viewed as a form of social therapy. The health benefit of friendship is a bonus spin-off that will only flow properly from a genuine friendship, just as happiness is a bonus spin-off of a well-lived life.

William Reville is an emeritus professor of biochemistry at UCC, understandingscience.ucc.ie