The title of the article is misleading, as the participants were reading on a tablet, not an e-reader. ("During the two-week inpatient study, twelve participan

The title of the article is misleading, as the participants were reading on a tablet, not an e-reader. ("During the two-week inpatient study, twelve participants read digital books on an iPad for four hours before bedtime each night for five consecutive nights.") Having used an iPad, a Kindle, and a Kobo, I know from experience that there's a huge difference in the quality and intensity of light emitted by the devices. At its lowest setting, an iPad emits much, much more light than an e-reader at its lowest setting, and the e-readers I've used have to get above 25% or so before they begin to match the light intensity of the iPad at its lowest setting. The displays also differ in the way they're lit: tablet LCDs are backlit, and e-readers are generally front-lit, with the light being pointed at the screen and bouncing back off it. I wouldn't be surprised if the blue/white light used on e-readers also affects sleep, but I think a study needs to be carried out using those devices before it can be concluded that they do.