Researchers are warning that loneliness and social isolation is becoming a greater public health threat than the widely discussed problem of obesity.
More and more people in the US are living alone, with declining marriage rates and fewer children - and psychologists are warning that the spread of loneliness is increasing our risk of premature death.
"Being connected to others socially is widely considered a fundamental human need - crucial to both well-being and survival," says psychologist Julianne Holt-Lunstad from Brigham Young University.
Over the weekend, she presented the results of two large meta-analyses on the connection between loneliness and premature mortality at the 125th Annual Convention of the American Psychological Association.
"There is robust evidence that social isolation and loneliness significantly increase risk for premature mortality, and the magnitude of the risk exceeds that of many leading health indicators," Holt-Lunstad explained in a statement.
This evidence has been gathered over the past several decades. In one meta-analysis from 2010, Holt-Lunstad and colleagues combed through 148 studies with a total of 308,849 participants.
Extracting data on things like social relationships, health status, pre-existing conditions and causes of mortality, the team was able to quantify a difference between socially isolated people and those with stronger relationships. Those with strong social relationships were 50 percent more likely to survive longer than those who were isolated.
"The magnitude of this effect is comparable with quitting smoking and it exceeds many well-known risk factors for mortality (e.g., obesity, physical inactivity)," they write in the study.
In another meta-review, which encompassed 70 studies from 1980 to 2014, Holt-Lunstad and her team found additional data on how death rates are affected by loneliness, social isolation, and living alone.
Crunching the data revealed that all three factors corresponded to an increased likelihood of mortality of about 26-32 percent. These numbers came from more than 3.4 million people from across North America, Europe, Asia, and Australia.
"Affluent nations have the highest rates of individuals living alone since census data collection began and also likely have the highest rates in human history, with those rates projected to increase," the researchers write.
There's increasing awareness of the negative health effects of loneliness and social isolation - studies have shown an increased risk of mental health problems and cardiovascular disease amongst others.
In the US, more than a quarter of the population is now living alone, and similar trends have been observed elsewhere in the world, including India and the UK, where loneliness is especially acute amongst older people.
"With an increasing aging population, the effect on public health is only anticipated to increase," says Holt-Lunstad.
"Indeed, many nations around the world now suggest we are facing a 'loneliness epidemic.' The challenge we face now is what can be done about it."
She suggests that we need to take collective action in tackling loneliness as a public health threat, from emphasising social skills training for kids at school to adding social connectedness as an item on your doctor's health checkup list.
At an individual level, it means actively focussing our attention on the relationships we have, as explained by Michelle Lim from Swinburne University of Technology:
Another promising way to tackle loneliness is to improve the quality of our relationships, specifically by building intimacy with those around us. Using a positive psychology approach that focuses on increasing positive emotions within relationships or increasing social behaviours may encourage deeper and more meaningful connections with others.
So make sure you get out a bit more, and talk to your friends more often - it's good for your health.
The research was presented at the 125th Annual Convention of the American Psychological Association, and you can see the studies here and here.