Last month, The New York Times reported on a series of initiatives in Britain to address an unusual concern: loneliness. Describing it as a “serious public health issue” affecting mostly senior citizens, the National Health Service, along with local governments and charities, has taken steps toward improvement. They have set up 24-hour loneliness call-in lines, built three hundred carpentry centers that double as social spaces for retirees, and even asked fire brigades to check homes for “signs of social isolation.”

At first glance, these efforts might seem like overkill. After all, what makes loneliness a significant public health concern over, say, obesity? Researchers from numerous (mostly Western) countries, however, have found that chronic loneliness — which, rather than physical isolation, is usually defined as distress that results from a difference between your desired social relationships and those you actually have — poses considerable health risks. In addition to obesity, these include sleep disturbances, immune system deficiencies, cardiovascular conditions, disordered eating, and depression. All of these are considered predictors of premature death, either directly or indirectly, and not only for the elderly.

Between twenty and forty percent of older adults report persistent loneliness in the United States and Europe, according to results from several longitudinal studies; but young and middle-aged adults also experience significant loneliness. New mothers, university students, and single professionals are especially prone.

And while loneliness is timeless — indeed, Jean-Jacques Rousseau, Emily Dickinson, and even ancient philosophers professed feeling cut off socially — experts think the emotion has proliferated in a unique manner over the last few decades. This is due to numerous factors, but urbanization, increased technology usage, and longer lifespans (ironically) seem to be at the heart of the matter.

In an interview with Fortune this June, Dr. John Cacioppo, who directs the University of Chicago’s Center for Cognitive and Social Neuroscience and has been studying loneliness for over two decades, explained that urban development has resulted in a lost sense of community. “We aren’t as closely bound. We no longer live in the same village for generations, which means we don’t have the same generational connections,” Cacioppo is quoted as saying, “That releases social constraints — relationships are formed and replaced more easily today.”

On top of this, social networks have prompted many to replace face-to-face interactions with virtual ones. Cacioppo noted that social networks are excellent facilitators of social contact, but they cannot replace the real thing. A study conducted in China found that students who scored higher on test that measured loneliness and shyness tended to also display symptoms of smartphone addiction.

Finally, as evidenced in part by initiatives in the U.K., the fact that humans are living longer adds to the puzzle. There are several reasons why older people feel lonely, including reduced transportation access, poor health, the death of a spouse, and retirement.

Should we urge our governments to take measures? It would not hurt. Besides Britain, numerous countries, including Singapore and Denmark, for instance, have acknowledged loneliness as a public health problem and are exploring solutions . Still, I think a simpler approach could be just as effective: be cognizant of loneliness in loved ones, friends, and in your self, and reach out accordingly.