It seemed to work at first, but now it's no longer working. I restarted the app, but still doesn't seem to work as described. I like how f.lux turns the screen close to amber color late at night, but it makes it a little difficult to read code, and raising the brightness helped, but Lumen sounded like a nice tool because I may not have to worry about manually increasing the brightness during nighttime. Oh and when it was actually working in the beginning, I tested out my two external monitors connected to my macbook, but it didn't seem to work on them. Anyway, I think the idea behind Lumen is very neat.