Take them forever if they work , why stop and get sick an maybe never find another med that works. I see chemical imbalance in a simple way, like 2 rivers running through your brain at the same speed , when something goes wrong like depression 1 river runs slower than the other throwing of the balance, SO you take AD,s and that speeds it up till they both run the same again, With BIPOLAR 1 river runs fast (mania,) the other( slow) for depression, in bad cases both rivers keep changing speed from mania to depression, so mood stabiliser,s are bought in has a back up the get the rivers flowing the same speed. This is the way I make it simple to understand in none medical jargon, weird I no but works for me. depression has 1 river to sort out , bipolar has 2. PS don't swim the rapid,s