Culture shock is the overall swing of excitement and depression that comes with being in a foreign country for an extended period of time. Almost everyone has some form of culture shock, but it is different for each person and each person deals with it in different ways.
It can sometimes happen abruptly from a situation or incident, or slowly build from small problems over time. Sometimes, incidents of culture shock can happen immediately upon arrival. Other times, it might be months until feeling some kind of culture shock. For me, there have been two periods where I've lived in Japan, now and study abroad in college. Both circumstances for living in Japan were entirely different, so the conditions of experiencing culture shock were entirely different, too.
Either way, when living in a foreign country, culture shock follows 4 (or 5) overall stages and the overall curve looks like this.
When people think of culture shock, they often think of it as something negative. But, the overall feeling of experiencing life in a new country is often met with excitement. There are so many new things to experience differently from your own country. New food, new buildings, new money, new people, new stores. If you're a fan of your new country, touching things that you've dreamed of for the first time is an amazing experience you'll probably never forget.
All of these new experiences raise your overall mood level, and we move up the curve.
If you're only in a foreign country for a short amount of time, especially on vacation or a very short study abroad, this is probably the only part of the curve that you'll experience. This was the case when I studied abroad. Every day felt like a vacation. Exploring Nagasaki and writing blog posts about it was an amazing adventure that had something new and interesting each day. I never experienced any cultural problems large enough to pull me down.
So, in short, the honeymoon phase is meeting differences in culture with joy and excitement.
The shock phase is the opposite. This is what happens when meeting differences between your countries and cultures has problems.
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