Originally Posted by xendula
^ Interesting. If true, then the Kobo Glo and Nook Glowlight would cause the same sleep deprivation, since they have a blue shine to them.
The amount of light is as important (or more so) as the hue. The Lighting Research Centre study that people keep referencing (Wood et al 2012) had to crank a full-size LCD tablet light to full brightness and expose people close-up for two hours before any significant melatonin suppression took place. The glowing frontlit devices on low are putting far, far less light into your eyes.
Out of interest, I set my Kobo Glo to high brightness, and put it next to my laptop, matched the laptop's brightness, then fiddled with the laptop's F.lux settings until they matched. A match occurred at a colour temperature of about 5400-5500: warmer than daylight, and way warmer than standard LCD settings.