This probably won't be a shocker for most of you, but researchers at the National Academy of Science published a study recently that concludes the "short-wavelength light" messes up the circadian rhythms that are responsible for sleep and suppresses the sleep-inducing hormone melatonin.
This light that's closer to the blue end of the spectrum is especially present in the display screens of eReaders and tablets, such as the iPad. So, just in case you were having doubts, bringing your iPad to bed isn't such a good idea for your health.
As a result of being exposed to tablet and eReader screens prior to going to sleep, people reported feeling less tired, and took longer to fall asleep and they also mentioned they were more tired the next day. So, what researchers advise is something that most of us know already - opt for a physical book instead. They also suggest that a non-illuminated electronic reader like the original Kindle might also work.
The study involved 12 healthy young adults: