xobs and I have a game we like to play when we live in Shenzhen for extended periods -- it's called "let's buy a soldering iron at 2AM". We'll hack until some stupid late hour and then get hungry, and go out to find street food and "something else", e.g. soldering iron, spare parts, phones, power adapters, etc. in the street markets of Shenzhen. So far, we have not been disappointed. That city simply does not sleep.

This is in part because the EU and US is awake during Shenzhen's nighttime, and if people waited until the morning to fill all the orders coming their way, they'd have to spend all day catching up.