Lessening the Blues
Blue light negatively affects your body at night more than redder wavelengths. Your circadian system detects the blue and senses a false daytime sky, with the artificial delay in nighttime contributing to sleep loss and other physical woes. The document Seeing Blue sums up the science of how the body interprets light at night. To reign in the harmful component, you should eliminate blue from your diet of lights at night.
The f.lux app automatically lessens the blue output on your electronic displays. The app gradually adjusts the screen brightness as twilight segues into night. The redder hue can be awkward at first, but if you need full color, say, to work on a PhotoShop project, you can simply override the app for the duration of your task.
A handy feature called f.luxometer compares different electronic devices and lighting types at different temperatures, with temperature being the Correlated Color Temperature (CCT) in Kelvins. For example, the iPhone5 at 6500K has a significant blue presence in the bell curve to the left, which is the region where your circadian system is most sensitive.
When the f.lux app kicks in, however, the screen's output is significantly redder, and the bell curve to the left isn't dominated by blue. Below is the same iPhone5 at at cooler 1900K. The Interntional Dark-Sky Association (IDA) recommends lights have a CCT of 3000K or less.
Those parents who tell their kids to turn off the electronics at night are actually on to something--more than they likely knew. I encourage anyone who accesses an electronic device to change your way of looking at color at night, and as the URL suggests, just get f.lux. Please, give it a try. You have nothing to lose but the blues.