“The best way to define it is in terms of the offline consequences,” said Dr. Elias Aboujaoude, director of Stanford’s Impulse Control Disorders Clinic and author of the new book “Virtually You.” “Are we suffering in terms of our cognition and attention spans because of all the time we spend online? Is our professional life negatively impacted because of all the nonessential Internet surfing we do at work?”

Too often, he says, the answer is yes.

Among the constantly connected, many say they suddenly lack the focus and attention span they once had. They find it harder to get through a book, movie, conversation or even article (where you going, reader?) without feeling the tug of technology. —All those tweets, apps, updates may drain brain.