How to fix dark screen after locking iphone 4 ios6? The last week or two my iphone 4 started dimming it's screen to almost black whenever I lock it. Then when I unlock it I have to get to the brightness slider and move the slider to restore light to the screen.

Can anyone explain why this is happening and how to fix it?
The algorithm for auto-brightness was adjusted significantly in iOS 6.

Rather than before where you would see an immediate change on turning on auto-adjust, now it's a more gradual process, and you can actually see the slider moving as it makes updates.

Also, another change is that the auto-adjust now works on the lock screen, so at night you won't be blinded, and in the day you can actually see the screen in day light.

Personally, I found it very annoying for about 2 weeks, and now I've adjusted to it, I find it works much better than before. If I want to manually control the screen, pointing it at a bright light causes it to brighten significantly, etc.

Finally, some sites have suggested that you can "tune" or reset it by turning auto-adjust off, setting the brightness to minimum, then turning auto back on.

Worth noting, that as I'd had to get my flashlight replaced right when iOS 6 came out, I actually assumed it had broken the ambient light sensor and I took the phone to the apple store because the auto-adjust switch didn't work as it had previously. The geniuses had no explanation for the new behaviour. I had to google it myself, and plenty of other people have complained about it.