There are many side effects of the electronic gadgets like :
1. we mostly only concentrate on them only not on other things like education and other aspects.
2. the children and even the elders are getting addicted to the electronic gadgets.
3. the decrease in the eye sight of the small children. like watchin TV or using pc for more time is harmful for eye's.
4. the electricity used by the electronic gadgets is more, so we need to burn more and more fossil fuels for it.
5.  because we are burning the fossil fuels more the global warming increases because the burning of fossil fuels releases many harmful gases.
hope so my answer is useful and mark as best if possible ...!