I have to wear mine all the time. When I was about 14, I was given some 'for reading' and then never wore them, which caused my eyesight to deteriorate dramatically, as a result of my eyes having to strain to see things, so now I have to wear them all the time otherwise I can't see properly at all. So I'd advise wearing them as much as possible if you can. However, some people say that wearing them too much is also bad for you.