Note: I guess this will only work for users who do not use the zoom feature for its actual use. Many people like the fact that in iBooks, one can reduce the brightness of the screen further than possible than you can across the rest of iOS. In actual fact, all this is doing is applying a filter to the screen to reduce its white point. However, you can use this same filter across the whole OS by using iOS's built in accessibility zoom feature: Open Settings General Accessibility Zoom Zoom Filter -> Low Light Zoom Regions -> Full Screen Zoom Then if you toggle Zoom to On and zoom all the way out using the three finger tap and swipe so the zoom effect is effectively disabled, you are left with a dimmed display. To access this option as a shortcut, you can set the accessibility shortcut (triple click of the home button) found under the Accessibility menu to enable Zoom. Then, whenever you need to dim the screen a little more than usual, triple click the button anywhere in the OS and voila! Sorry if this has already been posted, but it really helped me when using my phone in the dark! Next best thing until Apple allows something like f.lux to run.