I've seen F.lux mentioned on a couple of paleo / primal sites recently - a free program to reduce the blue light from your computer screen so that you can get a more restful sleep at night.
My problem isn't just with PC blue light, though; my husband and I often play Angry Birds or other games, or surf the web and check email on my Droid at night.
Does anybody know whether there's a version of F.lux available (or something similar) for smartphones?
There's an app called neyetLight (pronounced nightlight) in the android market that costs 0.99. It works similarly to the F.lux program for computers.
I've not seen anything on it on the iPhone App store. I'm inclined to think that it's not doable. It's plausible for apps to be able to control the blue frequency when running that specific application. However, those changes are sandboxed to that app only. It doesn't affect the phone interface or other applications. It might be doable with a jailbreak, but I can't say for sure.
I also can't speak to the Droid. Don't have any experience with it.
My recommendation would be just to dim the screen at night when using it. Not perfect, but I think it's the best you'll get.
I looked into this for my Android and I can't remember specific links offhand, but my conclusion was that it didn't actually seem to be possible at this point, even to write your own app. There's no mechanism for adjusting the colour temperature.
I like doing crossword puzzles on mine at night but have cut back on that.
I was similarly thinking that an amber screen filter would be the best solution. Perhaps a theatre light gel or just some cellophane?
Possibly of interest to ipad users, I got one of these: https://www.lowbluelights.com/detail.asp?id=77
Note that it is pretty flimsy; just a very thin and flexible piece of plastic with a cardboard surrounding that is supposed to stick to your ipad. Because of the matte screen protector I have on there, it doesn't actually stick, so I just use a chip clip to keep it on there, which works just fine (that's about the only use I have for chip clips these days anyway).
Once affixed it works really well in terms of reducing the ridiculously bright ipad screen at night and filtering out the blue light.
I also got a book light from those same people, which is pretty cool.
There's an app called Screen Filter available in the Market that lets you turn the screen brightness WAY down. It's the closest thing I've seen to F.lux.
You have to have Root access to your phone for it to work though.