周末逛完商場出來竟然出現頭痛、胸悶之類的反應。大概是因為商場人多、空氣稀薄的原因吧。

Mall hangover? refers to the headache, tiredness and sometimes nausea one gets after going to the mall, just like many may experience after heavy consumption of alcohol. A hangover describes the sum of unpleasant physiological effects following heavy consumption of alcoholic beverages, typically after the intoxicating effects of the alcohol begin to wear off. This is exactly where the term comes from.
“商場宿醉反應”（mall hangover）指逛完商場后出現的頭痛、疲勞及偶感惡心的癥狀，就跟人喝醉酒以后經歷的不舒服的感覺一樣。Hangover這個詞本來就是指喝醉酒以后、尤其是酒勁散去之后出現的不適反應。Mall hangover便是由此而來。

For example:

I was at the mall for like five hours and when I got home I had a major mall hangover.
我在商場待了大概5個小時，回家后就出現了嚴重的商場宿醉反應。

（中國日報網英語點津 Helen）