A simple solution I have been using at night with my ipad is to wear orange lens sunglasses. I have noticed a significant change in my ability to fall asleep at night since I started wearing them at night to watch TV or use my ipad. I have f.lux on my desk computer, but do not want to hack my ipad to put it on there.
I bought the glasses on Amazon for under $10.
I pestered a guy I know at Apple to get it into the App Store as a result of this thread. And I’m not talking an Apple Store Genius here. Still, I doubt it will do any good, but I feel better about it!
His reply implied he was already familiar with f.lux and likes it.