Screen brightness settings

Ok, so I know that if I hit F1 and F2 keys on my MBP it controls the settings for my screen brightness. What I have noticed over the past couple of nights though, It will be set on the 3rd or 4th bar. I usually keep it at the first bar (lowest setting) since I'm usually running off of the battery. Does anyone know why it would change itself? I didn't know if dim lighting had to do with any of it, becuase my room is very dark from time-to-time.

i know that osx messes with the brightness setting from time to time due to poweroffs, energy settings etc...

So like the setting could be reset just from going to sleep or something like that?

it changes if it's unplugged.

Not just that, the screen does react to changing lighting conditions (if it gets darker the screen brightness decreases, the system also turns keyboard light on and off).
I think you can disable this feature...