I live in Taiwan. My time zone is UTC+8.
I notice that the time interval between UTC 04:00 and UTC 06:00 is the most vulnerable time (being attacked by spams) of our site.
I have seen the questions like this one https://cs.stackexchange.com/q/13756/630 very often during that interval. I believe the reason is that our mods and users in north America already go to bed and those in Europe have not got up yet.
Today, I have seen 5 spams in that two hours interval. I already did everything I could. I downvoted them. I flagged them. I am not a high rep user. I did the best I could.
We need to do something about it. Otherwise, the users in Asia would think the stack exchange sites are not worthwhile participating.