[ChikkaChiChi]

If you want to use a screen at night and you don't want to mess with your sleep cycle, make sure you have a device with an AMOLED screen that has the ability to run a profile that uses red pixels only.

Samsung Android devices like the Note and the Galaxy S3 have AMOLED. On the Play Store, there is a free app called Galactic Night that will let you run the device in red only. Add on another free app called Screen Filter, and suddenly you have a device with perfect lighting that allows you to keep your night vision and let your eyes rest while you drift off to sleep. CyanogenMod used to have this feature; not sure if it still does.

Backlit LCD screens (even ones that use Flux or Red profiles) won't work because even the black pixels are backlit. I've tried using a jailbroken iPad with Color Profiles and it's just not the same.

Finally, you can use an e-reader but I recommend a light source you can add a red gel to. This will have the same effect.

Source: I've been reading on a screen before bed since the days of the Palm III. Also, I used to develop film in a real darkroom.