Symptom: you are working away on your laptop or tablet, and suddenly the screen dims. Moments later, it brightens. Annoying and distracting.
The reason is the ambient light sensor. Someone thought it would be smart if the brightness of the screen varied according to the level of ambient light. If the room is more dimly lit, your screen does not need to be so bright. Microsoft’s Surface Pro, for example, has this enabled by default.
The idea is reasonable, but the implementation is lacking. Instead of the brightness gradually varying so you do not notice it, it dims and brightens like a mad thing.
You can fix this in Windows 8 through the power options – no it is not in display options so don’t bother looking there.
If you have a battery/mains icon in the notification area in the task bar, you can right-click and choose Power Options. Otherwise, open Control Panel (desktop version), and search for Power options.
Now click Change plan settings for the currently selected power plan.
Then click Change advanced plan settings.
Now scroll down to Display and expand the tree.
The setting you want is Enable adaptive brightness. You can set this separately for mains and battery power. It does slightly extend battery life, so you might want to leave it On for battery and Off for when plugged in.
Then click Apply and close the dialog.