Why do my phone suddenly turn dim even with maximum brightness?

[kimberly12]

I have trouble with my phone screen's brightness. It suddenly turned dark. And even when I turn the brightness up to maximum, the screen still looks really dark.
After I let the phone sit for a while, the screen's brightness returned to normal. But when I unlock the phone, the screen flickered and then turned dark again.
What's wrong with my phone?

 

[mustang7757]

Welcome to AC!
Which Samsung note?
You have battery save on? Pull your notifications panel down and check if battery save toggle on?

 

[B. Diddy]

Welcome to Android Central! You posted in the forum for the ancient original Galaxy Note phone, so we're assuming you have a much more recent version.

Does this also happen in Safe Mode?

 

[Laura Knotek]

Are you using adaptive brightness? What happens if you turn adaptive brightness off?