f.lux changes the color of your Desktop depending on the time of day, warm at night and like sunlight during the day. When the sun sets, it makes your computer look like your indoor lights. In the morning, it makes things look like sunlight again.
People working at the computer at night often have problems falling asleep. The reason for this is cheating the body with an intense light of the monitor at a certain temperature. f.lux after setting the user's position and determining the type of external light is able to automatically dim and insulate or cool the image on the monitor to make it seem more natural to the time of day.
As a result, the picture will become darker and warmer or cooler (depending on the type of lighting chosen) with the fall of dusk and will return to its "daytime" colors at dawn. Set f.lux with kind of lighting you have, and where you live. f.lux will do the rest, automatically.
Daytime is whenever the sun is up in your location. By default, f.lux is at 6500K during the daytime, and does not change your screen’s color. Sunset is when the sun has set, but you are awake. If you are an early riser, this is also your pre-sunrise morning setting.
At sunset, f.lux will fade to 3400K, and turn off at sunrise. For large screens this setting is probably not strong enough to remove all alerting light. The f.lux preferences window lets you change and preview settings. There are several presets you can choose from. f.lux will default to the Recommended colors preset.