I have around -3.25 and astigmatism of -1.25, in addition to that I have eye-fatigue problems and have to wear a different prescription (a weaker one) for computer and reading).
Most of the day I won't wear glasses, unless I have to see things in the distance or small things or need to preform an eye-exam on a patient.
I wear contacts sometimes, mostly for night outs and sports. I also have a huge problem with seeing at night (that's how my vision problems started in the first place).
When I was 10 I noticed that at night I see worse then my friends and my brother. When I was 13 I started having problem seeing the board from the back of the class.