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What is the connection between loneliness and mental health?

By Colin Murray

Whether it be a shoulder to cry on, someone to run towards to share exciting news with, or simply a person to quietly sit with after a long day, companionship and social bonds are a big part of how we meaningfully experience our lives. This drive to connect — so strong in humans — is not new, but has been slowly developing for millennia. Group living and reliance on social bonds in primates goes as far back as an estimated 52 million years, meaning that social contact has been contributing to and shaping the evolution of humans since well before anything resembling the modern-day human evolved.

For this reason, it is shocking that one quarter of Canadians aged 14–24 years old and 10% of all Canadians reported that they always or often feel lonely, or that over half of American adults reported feeling lonely. These stats have resulted in what is now considered the epidemic of loneliness and isolation. The seriousness of this epidemic becomes even more apparent when we consider the physical and mental toll loneliness is having on people.

Of the people who reported always or often feeling lonely in Canada, almost 50% of them also report poor mental health, compared to just 7% who reported never or rarely feeling lonely.

So, are loneliness and mental health connected? Yes.

But what is actually causing this? What exactly is loneliness?

A person suspended in the air between two mirrored forest landscapes.
Credit: Pexel –

What is loneliness?

Everyone has experienced loneliness at one point in their lives. The emotion can be felt almost anywhere, whether it be traveling alone in a foreign country, a recent move to another city, or even at a party surrounded by others. Researchers think that loneliness could have developed in our ancestors as an alarm signal. It is as if your brain is saying, “WARNING! Social connections and community are lacking! You are now at risk to predation or a lack of food!”

“Loneliness is an evolutionary mechanism, a bit like thirst, pain, hunger, fear; it actually serves us… If we are lonely, we have an impulse to connect”, says Dr. Kimberley Brownlee, a professor at the University of British Columbia and Canada research chair in ethics and political and social philosophy. Brownlee’s research primarily focuses on loneliness and social human rights.

Loneliness may have evolved to keep us safe, but for most modern adults, a social network is not necessarily needed for protection or food. The importance of social connection — what was once a requirement to achieve these basic aspects of life — may now be more fundamental to our health than it was in our evolutionary past.

Dr. Mathew Lieberman’s book, “Social: Why our brains are wired to connect”, further explains this idea. Lieberman argues that Maslow’s hierarchy of needs, which places physiological needs as the most fundamental human need, was wrong. Instead, he suggests that social connection is the most fundamental of human needs. Without these social bonds, our ancestors would not have been able to organize themselves into self-sustaining communities, and newborns would quickly perish without the essential bond created between mother and infant. This social need remains ingrained in our biology throughout our lives.

Maslow's hierarchy places physiological needs at the bottom of the pyramid (left), while Lieberman believes belongingness and love needs (social connection) should be at the base of the pyramid (right).
Maslow’s hierarchy of needs (1954) and Dr. Mathew Lieberman’s suggestion (2013). Created with

Strikingly, one does not have to be alone to feel lonely. In fact, social isolation is only weakly associated with the feeling. So, if social contact is not necessarily the cause or ‘cure’ to loneliness, what could be driving this profound experience?

It ultimately comes down to a person’s perception that they are socially isolated, which can be inaccurate, says Brownlee. She continues to explain that chronic loneliness stems from a persistent and deep perception of isolation, which can result in a vicious cycle that impacts the way people respond to social situations. For example, someone will invest more time into a relationship that they perceive as satisfying, whereas the reverse is true for relationships that are unfulfilling — further harming their perception of the relationship and isolating them.

Loneliness is a complex and painful subjective emotional state that cannot always be within our control and can be increasingly difficult to break out of. This is partly because chronic loneliness can begin to change how we perceive social situations and our very nature towards others.

Loneliness and Health

“When [loneliness] starts to settle and becomes chronic, that evolutionary mechanism [tied to social connection] starts to overreact… our loneliness mechanism can start to be triggered in ways that make social connection seem threatening,” says Brownlee. Someone who is chronically lonely may begin to read social cues inaccurately. They may anticipate that relationships will be unfulfilling, defensively place more emphasis on independence and self-reliance, and find social situations increasingly stressful, both mentally and physically.

Research supports this notion. Scientists have observed that loneliness can result in increased bodily stress, as seen through an increase in circulating stress hormones, markers of inflammation, and changes to immune cells. Increases in inflammation and stress hormones have been known to affect health for decades. Therefore, it makes sense that loneliness is correlated with a higher risk of mortality across medical conditions, including alcoholism, suicidal ideation, depression, and anxiety.

To help put the risk of loneliness into context, researchers state that the lack of meaningful social connection is worse for someone’s overall health than smoking 15 cigarettes a day. Additionally, studies have shown that people reporting low social cohesion and social disruption have poorer antibody response to vaccinations and, as a consequence, have reduced immunity to viral infection, as studied in the context of the COVID-19 pandemic.

This ultimately results in a 50% decrease in survival rates for people experiencing loneliness.

Biological pathways involving stress hormones and inflammation are not the sole ways in which loneliness can affect health. Psychological and behavioral factors play a role alongside stress, and all three of these pathways influence the function and architecture of the brain.

How does social connection influence health? Three main pathways contribute. 1. Biology. 2. Psychology. 3. Behaviour.
How social connection influences health, from the US Surgeon General’s Advisory on the healing effects of social connection. (2023).

Loneliness and the Brain

For the first time, a recent study aimed to come to a consensus on the neurobiology of loneliness by compiling all known research about the impact loneliness has on the brain. Researchers found that loneliness was associated with structural and functional differences in many areas of the brain, including the prefrontal cortex, insula, hippocampus, amygdala and posterior superior temporal cortex.

These different regions have many overlapping functions, but together they are important for regulating our ability to perceive and interpret social situations appropriately.

The behavioral and psychological shifts seen in people experiencing chronic loneliness, including mental illness or the inaccurate perception of social cues, may be a result of the changes in these brain regions.

There is strong evidence suggesting that loneliness can contribute to real changes in our body and brain that can lead to severe physical and mental health issues no matter the individual. Fortunately, governments are taking these findings seriously and are beginning to address them.

Health Authorities are Taking Notice 

In 2018, the UK government appointed a Minister of Loneliness. Just this year, the United States Surgeon General published a public health advisory that highlights the importance of social connection and community, and the serious health implications of loneliness. However, Brownlee points out that Canada is far behind the UK and USA in terms of identifying loneliness as a public health issue and addressing it accordingly.

Loneliness is complex, and addressing it can be difficult. “Just giving someone a pill to take away their feelings of loneliness would be to do a disservice to them”, says Brownlee. This kind of treatment would not actually get to the heart of the problem, just address the symptoms.

Being or searching for a shoulder to cry on, sharing and listening to exciting news, or just being present with people is likely the best way to start tackling the epidemic of loneliness. We know our bodies need water, food, and warmth to live a comfortable life. It’s time we also acknowledge they need social bonds and connection.


Thank you to our community member who asked this question! If you have any questions about mental health, send them over to our questions tab or reach out to us on Instagram or Twitter!


If you’re interested, check out some of the sources I used in researching this answer! All sources used for this answer are strictly evidence-based.

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