Smartphones are what I think of as "attention capturers" which are able to completely capture almost anyone's attention span for a significant amount of time. Other attention capturers include computers[0], video games, TV, books, chess. Each of these has varying capability as attention capturers but it is safe to say that smartphones are the strongest attention capturer for most people.
I believe that using any attention capturer for long periods is not healthy and should be avoided. The hard part for me is actually finding anything else to do in a new city without family/friends. Especially on a Tuesday night after work where it is less possible to go to a bar and talk to strangers.
I've noticed several side effects such as decreased attention span, decreased sociability, decreased desire to do anything other than your preferred method of attention capturing.
Frankly I just think that many of these things are simply addictive and, with an appeal to naturalism, I don't think it is what humans were meant to do. Increased smartphone use or TV watching or video games probably almost never results in increased happiness over the long term.
Not to mention the ability to use attention capturing as a way to hide from one's own emotions.
I believe that using any attention capturer for long periods is not healthy and should be avoided. The hard part for me is actually finding anything else to do in a new city without family/friends. Especially on a Tuesday night after work where it is less possible to go to a bar and talk to strangers.
[0] Smartphones can be included here.