I read a book entitled The Shallows: What the Internet is doing to our brains

I'll save you from reading the book by summarizing that yes, the over stimulation of the internet is definitely BAD news for our brains.

For the last five centuries , ever since Gutenberg’s printing press made book reading a popular pursuit , the linear , literary mind has been at the center of art , science , and society . As supple as it is subtle , it’s been the imaginative mind of the Renaissance , the rational mind of the Enlightenment , the inventive mind of the Industrial Revolution , even the subversive mind of Modernism . It may soon be yesterday’s mind.
(p. 10)
Calm , focused , undistracted , the linear mind is being pushed aside by a new kind of mind that wants and needs to take in and dole out information in short , disjointed , often overlapping bursts — the faster , the better .
(p. 10) 

The secret to not going retarded thanks to excessive internet use is mindfulness practice.