There is a truism, often bolstered by pseudoscience, that people in the country are healthier than people in the city. Certainly there are many health problems associated with the metropolis. But it turns out that urbanites are often in better shape and live longer than their rural counterparts.
Most of our data on the health of people in cities comes from public health studies, like the one conducted by County Health Rankings in the United States, that compare the general health of people in various regions. Questions about regional health become more complicated when we look at it in a global perspective — partly due to vast differences in data-gathering practices — so in this article I'm going to focus mostly on studies that have explored U.S. health.
I began by saying that city dwellers are by and large healthier than their non-urban counterparts. But that's not true in every respect.
If you live in a city, you're more likely to develop asthma, allergies and dry eye.
People in cities, especially children, seem to be slightly more prone to allergies and asthma. One study suggests this is possibly because children in low-income urban areas are exposed to more toxins and stress at an early age, or suffer from more untreated respiratory illnesses. A similar pattern, with more asthma in cities, appears in a study of Scottish people. However, at least two U.S. studies suggest that asthma is equally prevalent in both the city and the country but isn't treated as aggressively among kids in the country. So it may appear that there are more asthma cases in cities simply because there are more health resources for parents who want to treat their kids — and thus, more parents report that their kids have asthma.
Also, city kids have more allergies, at least according to one study. This is a difficult claim to analyze, in part because there is so much disagreement over what causes allergies and even whether some conditions should be classified as allergies at all. Nevertheless, one theory behind this statistic is the "hygiene hypothesis," which suggests that people's immune systems don't grow as robust in artificially antiseptic and decontaminated environments. And such super-clean environments are more common in cities than in the country.
So city toxins may be causing asthma, and hyper-cleanliness may be causing the allergies. But dry eye is definitely caused by pollution.
A higher percentage of urbanites will suffer anxiety disorders, mood disorders and maybe even schizophrenia.
One study found that people in U.S. cities do have higher rates of depression than people in rural areas, while another suggested that the prevalence of mood disorders is 21 percent higher in urban areas than rural ones, while the prevalence of anxiety is 39 percent higher. As many as ten studies have found that some cases of schizophrenia may be linked to urban environmental factors.
Why do cities affect people's mental health so negatively? Researchers who published a study in Nature suggested that it's possible humans' brains develop slightly differently in urban areas, predisposing them to stress-related disorders. They found that the amygdala, which processes emotion, was more active in people who were currently living in a city. In addition, the cingulate cortex, which helps regulate the amygdala and processes negative emotion, was more active for people who were raised in cities. The researchers caution that this doesn't mean that cities drive people crazy; it just means that people in cities may be more predisposed to stress-related conditions.
City dwellers have troubled circadian rhythms.
Finally, as if you weren't stressed out enough, cities are likely to affect your circadian rhythms, or your body's internal clock that tracks day and night. Many studies have shown that lights at night confuse this internal clock, as does urban night shift work. There are a number of health consequences when your circadian rhythms get out of whack, including depression, insomnia, inflammatory diseases, diabetes, and even cancer.