Try a Restart.
Press and hold the Sleep/Wake button for a few seconds until the red "slide to power off" slider appears, and then slide the slider. Press and hold the Sleep/Wake button until the Apple logo appears.
Resetting your settings
You can also try resetting all settings. Settings>General>Reset>Reset All Settings. You will have to enter all of your device settings again.... All of the settings in the settings app will have to be re-entered. You won't lose any data, but it takes time to enter all of the settings again.
Resetting your device
Press and hold the Sleep/Wake button and the Home button together for at least ten seconds, until the Apple logo appears. Apple recommends this only if you are unable to restart it.
Or if this doesn't work and nobody else on the blog doesn't have a better idea you can contact Apple.
Here is a link to their contacts with most of the information below.
I've only tested this over the last 20 minutes so if someone else could verify this test. This has worked on my iPhone 5s and iPad Air.
I remember the fix in iOS 6 was to go into Brightness under Settings and you would need to set a minimum value by turning auto-brightness off and then adjusting the slider to the most comfortable level while in a dark room. Once you set the slider to the most comfortable level you would then turn auto-brightness back on and the slider would never go below that minimum set value.
In iOS 7 this setting has one change...
Do not turn off auto-brightness. Just set the slider to the most comfortable minimum value from the Brightness settings while auto-brightness is turned on and the slider will not go below that set minimum value.
So far my iPhone and iPad are both opening at a comfortable level and not going below the minimum value I have set. Give this a shot and see if it helps if you're noticing your screen is way too dim with auto-brightness turned on.
Hope it helps!
Message was edited by: BostonShawn77 Edited a typo.