I happened upon your post and thought I would give you my experience with this. I usually post on the MS board so I have very litte experience with depression. I am a fifth grade teacher and a mom. I have taught many many students who have ADD and my oldest son was diagnosed with it when he was 7. ADD is a spectrum disorder which means you can have a low level of attention and focus disorders or it can be quite severe. It is considered a chemical disorder of the brain. In children is appears very much like the sleepy driver trying to stay awake. The driver does everything he can to stay awake: he plays loud music, he changes position, he slaps himself, rolls down the window - all in an attempt to stay awake. After the driver either gets some sleep or some caffeine, he can settle down with all of the movement and concentrate on driving. That is how it is for kids - when you stimulate a sleepy ADD brain, the body can stop trying to wake up the brain and the child can focus. I don't have a great deal of experience with adult ADD. It is very hard to diagnose due to the inability to actually sample brain chemicals. The usual way to diagnose ( after checklists and an exam ) is to try a med and see if it works. This can be a bit scary. ADD meds are psycho-stimulants and if you do not have ADD then those meds can make you feel awful although it is temporary.
Most PCPs will let you have a trial of an ADD med. Common meds are Ritalin, Adderall, Concerta, Strattera and many of those come in an extended form. Go see your doctor and see what he or she has to say. Good luck.
Love and prayers,