[fdkz]

Use the home button triple-click trick for night reading.

http://lifehacker.com/5957534/invert-your-phones-colors-for-...

Another thing that really helps is f.lux for iphone:

http://justgetflux.com/ios.html

But this sadly requires jailbreaking.

[mixmastamyk]

Thanks, I do remember that. There is the problem though of those apps which use a dark theme, that therefore become light upon negative view. Hence, why I'd prefer a single theme enforced.