Loneliness has emerged as one of the most pervasive and unrecognized emotional conditions in our modern world. The unprecedented increase in single-occupant households and the growing dominance of digital forms of communication have left a greater proportion of the population feeling isolated than at any other time in history. Loneliness has been trivialized as merely an emotion, or worse, a state of mind that one can easily overcome if they just set their mind to it. However, research has found that loneliness is a signal deeply embedded in our biology, and one that has observable effects on the human brain.
Like Hunger
At a neurological level, loneliness is more like a hunger pang, a motivational signal that compels us to seek others as if our survival depends on it, much as a growling stomach impels us to seek food. In multiple experiments, social isolation has been shown to light up the same neural circuitry that’s fired up by physical starvation.
The most striking of these experiments came from a 2021 paper published in Nature Neuroscience. Neuroscientists at the University of California, Los Angeles, recruited 40 healthy adults and subjected them to two forms of deprivation. In one session, volunteers were alone for 10 hours. In another, they fasted for 10 hours. After each session, the scientists took brain scans of the participants with a functional magnetic resonance imaging (fMRI) machine and compared the results to baseline.
The brain areas that lit up when the participants felt the pang of loneliness were the same areas that were activated when they were experiencing strong hunger. The brain was treating the lack of a social connection as deprivation, as a need that must be satisfied. In other studies, loneliness and social rejection have been associated with greater activity in parts of the brain that process uncertainty, rumination, and stress. In one review, these signals were said to trigger “alarm-like” responses in the brain, prodding us to seek social contact for our psychological well-being.
In other words, loneliness is not a minor inconvenience. It’s a biological craving, one that the brain takes as seriously as food or water.
Less Trusting
Social connection is wonderful, but when we feel isolated, it’s difficult to believe that it’s possible. Chronic loneliness can uproot your ability to trust others, and the next study in our series shows how.
Published in 2021 in Advanced Science, this experiment compared 42 people with a long history of severe loneliness with a demographically matched control group. The participants were asked to play a game where they could choose to keep some imaginary money or share it with a partner. This “partner” was also given the chance to triple the shared amount and then give back some of that profit. The game both required trust and exposed participants to risk.
The outcomes revealed that lonely participants were more risk-averse; they shared much less of their imaginary money than the control group, indicating lower trust levels and social risk-taking. This was then confirmed with brain scans: lonely participants showed less activation in trust-related brain areas, including the amygdala, the hub of emotion processing in the brain. Earlier studies have also found smaller amygdala volume in lonely people, which may be connected to smaller social networks: a type of neurological punishment for social withdrawal.
The data from this experiment was also confirmed at the biological level. Blood and saliva samples showed that lonely participants had lower oxytocin levels and did not experience mood-elevating effects of small talk like the non-lonely group. They also reported significantly more distrust toward the research assistants themselves, despite never being shown any reason to.
