I've noticed that my vision and attention span become drastically reduced after using my computer for any given amount of time. Same pplies to TV and phone, as well. The effects, for me, of using the interwebs is like using narcotics, wherein I seem to be hypnotically attached to my screen and the most inane of subjects become noteworthy and worth investigating.
Currently writing this from my Kindle, which is suffering, but at least I can read a book after, without my brain turning into figgy pudding. In short, I'd imagine that LED backlights are to blame. There iks no such thing as a free lunch.