f.lux : adaptive light settings for your devices
I'm hooked on f.lux.
F.luxometer is free software that you can install on your phone, laptop or iPad, that reduces the amount of blue light in your screen display and also adjusts accordingly throughout the light cycle of your day and night. That way, if you're logging some email time late at night, the blue light is dimmed so significantly and your screen takes on a muted yellow glow so your eyes and brain won't be receiving all that bright blue light, confusing your sleep cycle and throwing off your night's sleep. I find it so much more comfortable and soothing. Definitely give it a try.