Chinese mattresses are HARD. It's not that they are extra firm spring mattresses--they are one solid piece of wood?...concrete?...actually, I'm not sure what's inside.
This is my mattress. There are no springs inside. I can't overstate how hard it is. Sleeping on it at night is identical to sleeping in a sleeping bag on a linoleum floor (the sleeping bag representing the sheets, not the mattress). But before you pity me too much, you should know that these are standard in China.
After talking with a number of Chinese students here, I've discovered that most Chinese people consider hard mattresses better for your health than soft ones. One student told me that once his sister's back was hurting, and the doctor told her the problem was she was sleeping on a soft mattress. Once she changed to a hard mattress, her back was healed.
Some students I talked with said they have spring mattresses at home, but even they still thought that hard mattresses are better for your health--even if they are less comfortable. According to the students I talked with, all the Chinese students here sleep on hard mattresses in the dorms. At home some have spring mattresses, but the majority opinion in China is that hard mattresses are best for your health.
How have I coped with it, you ask? I still wake up at least once a night with numbness in my legs or arms. My nerves aren't used to it yet, I guess. I had a severe backache one day so that I couldn't even wear a backpack.
But I'm getting used to it. I look forward to going to bed. It just takes some getting used to. I'll let you know if I experience any of the health "benefits" they talk about.