When I used to live in Japan, the summers were really too much for me, especially when going to bed. The strange thing is that all the (Japanese) people would strongly advise me against leaving the air conditioner running while I sleep because this is somehow very bad for people's health.
On the other hand, I also used to live in Thailand for a while, and I never heard anybody say something of that nature-- and their weather is steaming hot. Similar with other countries I've lived in. I only heard this air conditioner thing while in Japan.
So my question is: Is there really anything at all to be concerned about when running the air conditioner while sleeping? Or is this more like a Japanese urban myth?
By the way, I always used to set the air conditioner in air drier mode, rather than air cooler mode. It felt as cool, except that it was dry.