Jailbreak Only: F.lux - Automatically Change Screen Appearance

A jailbreak tweak called f.lux promises to automatically change the appearance of an iPhone's screen, but not in the way you might expect. While Apple's iOS already features an automatic brightness toggle, f.lux changes the screen's warmth based on the time of the day. Once downloaded and installed, users can configure f.lux via a pane in the Settings app. You can choose a display for the daytime ("Normal," "Midday Sun," "Fluorescent" or "Halogen"), and one for the night ("Fluorescent," "Halogen," "Incandescent" or "Candle"). Each level makes the iPhone's screen appear "warmer," so to speak, and is designed to better suit users' surroundings during the evening and night. According to Redmond Pie:

When installed, f.lux warms up the colors of the iPhone display when the sun is setting and does the reverse in the morning by returning the device to its native daylight colors. There is actually a great deal of science and research applied to this topic, with a large percentage of technology users believing the display should be about brightness rather than actual color. It has been proven that blue light is great for the bodies circadian rhythm [sic], however in the evening it detracts the body from sleep and becomes extremely detrimental to health in the long-term.

You can enable a "long transition" period between the two lighting modes (this isn't available on older iOS devices, however), and the tweak can also be disabled when users' engage in color-sensitive work. Currently, f.lux is available to download in the Cydia Store for free, and is compatible with iOS 4.0 and above. A Mac version of f.lux can also be downloaded at the jailbreak tweak's website.