Am I the only one that keeps the same value for night and day? I have it set to 5400K regardless of the hour. I like the subtle warm glow to remain constant instead of fluctuate.
While a bright monitor can reduce the quality of your sleep at night, I actually read somewhere (sorry, can't find it now) that a bright monitor at daytime can be beneficial for your circadian rhythm if you don't get exposed to much sunlight otherwise.