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Loneliness is one of the most paradoxical human experiences. On the one hand, it can be a space of profound inner richness, a necessary refuge for connecting with our authentic desires and reflections, the ones the world’s constant noise tends to silence. For many, achieving a degree of solitude is, in fact, a triumph: women who claim an intimate space of their own beyond the historical role of caregivers, young people who find a personal corner amid overcrowding, victims of violence who manage to escape oppressive environments.
But it can also cause great psychological and physical distress when it is associated with a sense of disconnection, a gap between the relationships we long for and the ones we have, and the question of how much loneliness has to do with not possessing sufficiently attractive qualities (beauty, charisma, intelligence, etc.) to attract other people’s interest.
In English, the distinction is clear: solitude is the physical, neutral, and sometimes desired state of being alone, while loneliness is the subjective experience of feeling alone. In Spanish, both realities are lumped together under the same word: soledad.
To understand its complexity, it helps to be rigorous about definitions. Being alone is the objective condition of lacking physical company, a state that can be neutral or even positive. Feeling lonely is the subjective experience of disconnection, that sense of relational emptiness that can occur even when one is with others.
Social isolation refers to an objective scarcity of connections, a structural condition, such as living alone or having a very small social network. Then there is hunger for touch, the unmet need for affectionate physical contact, the lack of hugs or a handshake.
And finally, there is desolation, a concept developed by Mexican activist Marcela Lagarde to describe a state of political and social abandonment. Desolation occurs when someone is left without networks of care not by personal choice, but because collective support systems have been dismantled, with no prospect of reintegration. It is loneliness imposed by the structure.
A global alarm has been raised over these negative facets, over loneliness as pain rather than choice.
The silent epidemic and its numbers
In 2023, the World Health Organization declared unwanted loneliness a critical public health threat. The problem is global, widespread, and growing.
An estimated one in four older adults experiences social isolation. In 2021, 79% of young people between 18 and 24 in the United States reported feeling lonely. A WHO global estimate put the figure at one in six people experiencing significant unwanted loneliness by 2025.
In Latin America, according to a 2022 Gallup study, Bolivia tops the list at 31%, followed by Chile at 30% and Argentina at 28%. The Inter-American Development Bank reports that 58% of young people in the region feel disconnected from their community.
The trend is unmistakable. Since 1976, the rate of loneliness among young adults has continued to rise, surging during the pandemic. Longitudinal studies in the United States confirm a collapse in community life: the share of people who socialize with neighbors more than once a month fell from 61% to 39% over four decades. The General Social Survey, which has been conducted since 1972 (generally every two years), shows a sustained decline in the size of people’s networks of confidants: more and more people report having no one to discuss important matters with. The percentage of men who say they have no close friends has quintupled since 1990. The American Time Use Survey, which records in minutes how people spend their day, confirms that time spent interacting in person, especially with acquaintances and neighbors, has been declining since before the pandemic.
The pandemic did not create the problem, but it pushed it to unprecedented levels.
Why it is a health emergency
A key epidemiological study that followed 300,000 participants for an average of 7.5 years found that chronic loneliness can be as harmful as smoking fifteen cigarettes a day. It increases the risk of premature death by 26%, exceeding the risks associated with alcoholism, physical inactivity, and obesity. It is associated with a 29% increase in the risk of heart disease and a 32% increase in the risk of stroke. Several mechanisms explain this, and they operate in a cascade:
First, there is the biological mechanism: loneliness triggers the constant release of cortisol, the stress hormone, causing systemic inflammation, elevated blood pressure, and a weakened immune system. The body lives in a constant state of alert.
Then there is hunger for touch. Deprivation of physical contact, hugs, or caresses also sends cortisol levels soaring. It also reduces the production of oxytocin, the hormone associated with bonding and calm. We experienced this globally during the pandemic, but in normal times, more than 20% of people in the European Union live alone. The contact crisis is a physical dimension of the epidemic.
A behavioral mechanism is also at work. People who are lonely may neglect their physical well-being because a lack of support networks makes it easier to opt for unhealthy foods, avoid exercise, or put off doctor’s visits. It is a spiral in which loneliness damages health, and declining health deepens isolation.
Then there is the psychological mechanism. Without close emotional support, anxiety and depression find fertile ground. Sleep gets worse, and the brain, in a state of alert, struggles to get restorative rest, feeding the cycle.
Finally, there is the mechanism of missed opportunities. Social connections are not only an antidote to pain, but also engines of opportunity. Sociologist Mark Granovetter showed that weak ties—acquaintances, neighbors, or colleagues—are the ones most likely to open doors for us, socially or professionally. Even casual interactions with the kiosk owner or a neighbor combat invisibility and foster a sense of belonging. When we isolate ourselves, we lose not only comfort, but also opportunities and possible futures.
The challenge of measuring the invisible
Quantifying loneliness is often a complex task because it is a subjective experience, but there are tools that act as thermometers for the social fabric.
The UCLA Loneliness Scale, an international standard, does not use the word loneliness to avoid bias. It asks how often a person feels they lack companionship, have no one to turn to, or find that the people around them do not share their interests. The De Jong Gierveld Loneliness Scale, meanwhile, distinguishes between emotional loneliness, the lack of an intimate bond, and social loneliness, the absence of a broader network.
Other measures are more structural. For decades, the General Social Survey in the United States has asked about the size of people’s networks of confidants and how often they get together with neighbors. The American Time Use Survey makes it possible to calculate actual exposure to in-person interaction by recording who people spend their day with and what activities they do. On a global scale, Gallup and Meta surveys simply ask how lonely a person felt the day before.
This range of strategies for measuring loneliness is a symptom of its complexity and also of the need to put it on the agenda. There is no single percentage that can represent the share of the population experiencing it: there is a spectrum, depending on which layer of the problem is measured and how the question is asked.
Policy implications: multiple solutions
Beyond the range of figures, there is consensus that this is a phenomenon that needs to be addressed. Unwanted loneliness—especially in the form of desolation—is an individual and social distress with measurable medical consequences. It is highly prevalent and growing, its biological harms are proven, and its causes are structural and systemic.
That is why the solution cannot be a retail one (dating apps, coaching), but must take multiple approaches—in other words, be structural: rebuilding the infrastructure of care and spontaneous connection with the same seriousness with which a sanitation system is planned.
Possible lines of intervention include:
- Housing policy: reward community-oriented designs and shared spaces, not just the efficient use of individual square footage.
- Urban design: prioritize plazas, benches, libraries, and accessible, safe third places conducive to chance encounters.
- Labor policy: recognize time for care and community; challenge presenteeism and fragmented remote work.
- Public health: incorporate social connection assessments into routine checkups, as regularly and naturally as blood pressure is measured.
The epidemic of unwanted loneliness, of feeling alone, experienced by the people at the heart of this book’s chapters, is the clearest sign that we have already crossed a threshold of tolerance—or of harm.
