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This Is Your Brain on Loneliness

The evolutionary response that keeps you isolated, and how to overcome it.

Key points

  • Feeling lonely can cause hypervigilance, a state in which we see rejection and social threats everywhere.
  • Once we are hypervigilant, the risks of social interaction outweigh the benefits, creating further isolation.
  • Feeling rejected sabotages our efforts to connect with others, creating a self-fulfilling prophecy.
  • To overcome hypervigilance, we must learn to question our fearful responses and focus on empathy instead.
Source: Solominviktor/Shutterstock Standard License
Source: Solominviktor/Shutterstock Standard License

Many of us may feel a bit left out or isolated on this Valentine’s Day. For some, this is a passing melancholy, but for others, it’s more serious. Everyone experiences loneliness sometimes, but most people don't know that it can trigger an evolutionary-determined response that undermines our ability to connect with others, creating a cycle of pain and isolation.

Social Isolation Causes Hypervigilance

Animals (whether fish, caribou, or humans) that find themselves on the periphery of their social groups are the ones most at risk from predators. Being in that type of danger causes the animal to go into a self-preservation mode called hypervigilance, in which it is on high alert for possible threats. This includes social threats, which can feel as keen as any other kind.

Once in a state of hypervigilance, we experience rejection whenever we try to engage with others. Any possible sign of lack of interest jumps out at us, the way you notice every restaurant sign you drive past when you’re starving. Things start to look like they might be restaurants that really aren’t. Every unreturned phone call or text becomes a sign that we don’t matter to that person. A single bad date seems to mean we’ll be alone forever. And we tend to dismiss any evidence or arguments that might refute our worst suspicions.

Although these distorted response patterns increase the pain of loneliness, they also serve a purpose. As the late University of Chicago professor John Cacioppo noted, the evolutionary positive of this suffering is that it compels us to take action to foster and repair the intimate relationships without which our sleep, health, and longevity (not to mention our happiness) are all impaired. Without the pain of loneliness, we might neglect those loving social connections that are of utmost importance to our well-being. But like aspirin that heals in small doses but harms us in large ones, too much isolation can have serious mental and physiological consequences that amp up the dangers of social situations to the point where they become aversive and almost impossible to navigate.

How Hypervigilance Can Trap Us in Loneliness

Hypervigilance makes us feel the negative aspects of social interactions far more keenly than the positive ones—a friend’s one crabby remark seems more significant than the two hours of enjoyable conversation that went with it. Under those circumstances, it can seem hardly worth seeing anyone at all—even as we desperately crave intimacy. Just as bad, when we feel lonely and consequently under attack, we become prickly and defensive, disengaging the empathy that lets us connect positively with others and depriving us of our social skills when we most need them. Sadly, these responses can be triggered even by those we love, when we feel rejected by them.

Unsurprisingly, loneliness causes depression. Surprisingly, Cacioppo found that (after controlling for other correlated factors such as stress level) depression does not cause loneliness. It would therefore be wise for every person who feels depressed or suffers from social anxiety to consider whether their unhappiness really stems from a need for warm, intimate relations, regardless of whether they are a loner or a social butterfly; the person who seems like the life of the party, sought after and surrounded by laughter and conversation, might on the inside feel utterly alone.

The Path Out of Loneliness Can’t Be Walked Alone

It is not the number of our social connections that determines loneliness, but their quality—even one close friend may be enough for a fulfilling social life, while hundreds of superficial or incompatible ones may only exacerbate one’s isolation. And one of the loneliest places to be is trapped in an intimate relationship with a person we don’t feel genuinely connected to. We all need at least one person we can rely on and can be vulnerable with, and with whom we have a warm, supportive relationship.

Loneliness is one thing that cannot be fixed without help despite our beliefs that we should be able to solve problems on our own; indeed, without making ourselves deeply vulnerable to another person. Unfortunately, once we’ve fallen into the trap of hypervigilance, every attempt to create social connection can be sabotaged by our increased sensitivities to rejection—unless we learn to become aware of this process and stop allowing it to drive behavior that impairs rather than repairs our relationships.

Taking Off the Blinders of Hypervigilance

To accomplish this, we need to be keenly aware that feeling isolated creates biases and filters that change how we experience and interpret social interactions, and we need to teach ourselves to question them. The goal is not to go through life in optimistic ignorance, unaware of social competition and danger, but to scrutinize our fears and assumptions. Does treating the distance to a group of strangers at a party like a bed of hot coals make sense? What’s the worst that could happen if we cross it? Might the long-term rewards of making a new friend outweigh the risk of rejection?

As meaning-making animals, unlike the caribou and fish, we have enormous power to shape our own experiences and decide how we will react to them. When our interpretations are colored by hypervigilance, we see rejection and attacks everywhere and respond by withdrawing into further isolation or lashing out. But if we can take off those discolored lenses and re-engage our abilities to empathize, we would find that there’s a good chance that person across the room might be feeling lonely too, and in need of some extra kindness. Shifting our focus from fear and hurt feelings to warmth and receptiveness can begin the journey out of isolation and into the comfort and joy of love that we all seek.


Cacioppo, John T. & Patrick, William. (2009). Loneliness: Human Nature and the Need for Social Connection. W.W. Norton Company.

Murthy, Vivek H. (2020). Together: The Healing Power of Human Connection in a Sometimes Lonely World. Harper.

This also appears in The Huffington Post

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