Ah, Paris, the City of Lights. Every year, more than 45 million people visit the city but roughly about 1 million of those starry-eyed tourists (mostly Japanese) fall sick with what has been dubbed the Paris Syndrome - what could cause such a strange effect?
Dan Lewis of Now I Know (That's Half the Battle!) explains:
Paris Syndrome is marked by a psychiatric breakdown suffered by the visitor, often including physiological side effects such as dizziness, an increased heart rate, and otherwise unexplained sweat. Extreme cases come with increased anxiety, a sense of persecution, and even hallucinations. Most of those affected are Japanese, but on occasion, a non-Japanese tourist will fall prey to the syndrome.
The cause? Most likely, it's a mix of a few factors: jet lag from the long trip; elation (similar to Stendhal syndrome) from taking a once-in-a-lifetime vacation; the language barrier; and, most critically, culture shock. As the BBC noted in its discussion of Paris Syndrome, "[m]any of the visitors come with a deeply romantic vision of Paris [but the] reality can come as a shock. An encounter with a rude taxi driver, or a Parisian waiter who shouts at customers who cannot speak fluent French, might be laughed off by those from other Western cultures. But for the Japanese - used to a more polite and helpful society in which voices are rarely raised in anger - the experience of their dream city turning into a nightmare can simply be too much." And, also according to the BBC, the Japanese embassy there takes culture shock seriously, staffing a 24-hour hotline for citizens and expats who suffer culture shock while in La Ville-Lumière.