According to this Harvard Medical School study light (of the color blue and bright variety) is bad for your health specifically if you are trying to sleep when it gets dark at night. In case you need to use your Mac at night the free app f.lux will automatically change the color temperature of your computer to match the time of day of your location. This is accomplished by using your IP address' GPS location. As of this writing f.lux changed my Mac's original setting to 1900K. This is equvialent to candle light. Do not worry you can disable the change of color temp and restore your original settings and disable the color temp change for current apps in use. If you do color critical work then by all means dont change it. For those who need to work in the night and be able to sleep as soon as you're done then this is really helpful. Incidentally FireFly LED sells color red LED night lights that consume as little as 0.5W of power and lasts 50,000 hours. Just wish it was 0.05W with lm/W efficacy of 115 or more.