Recently my iPhone 4s stopped sleeping. I'd receive a phone call or a text, then after I was done, I'd lay my phone down and it'd NEVER sleep.
I looked at all the settings and then gave up and called my daughter who works for Apple. I explained the situation and she told me to look into the "Settings|General|Auto Lock" settings page and make sure it wasn't set to "Never".
The issue was that, for the past ten months I had been working on a contract for a company that used Microsoft Exchange. Having their email on my phone forced me to use the passcode feature (which I HATE) on my iphone. Once I no longer needed access to their stupid exchange email (I hate Exchange as an email server. It seriously sucks. It's a classic example of Microsoft's "Embrace and extend" model gone awry. But let's not get into it), I deleted it from my phone and disabled the stupid passcode. While doing that I was also prompted to change a value called "AutoLock". Since I didn't want to automatically lock my phone anymore, I set it to "NEVER". That was a mistake. AutoLock is the feature that makes your iphone sleep when you are done with it. You WANT that feature set to at least one minute. Never is bad. Never choose Never.
So... after setting my "Settings|General|Auto Lock" to "One Minute", my phone now sleeps properly.
I feel sorry for those of you who don't have a kid who is a "genius" at Apple, while I simultaneously envy you. You have no idea the eye-rolls I get from my own kid when I ask her for help with Apple technology. HEY! Didn't I once feed you applesauce shortly before you puked it back all over me?! And let's not even go into the "pokies" incident.
Maybe this is what my dad meant when he said, "I hope you have ten kids just like YOU!"
I always thought it was a native American blessing of some sort. Maybe not :-/