This could be coincidence, but I started taking a vit.-min. pak from costco that my girlfriend had bought but never finished cause she didn't like taking 6 pills a day. I ran out of my Centrum one a day and asked her if I could have hers. Well after a couple weeks I noticed I was more sharp at work. I could focus better. It was that noticable. I wondered why and one day looked at the box of vitamins I was taking and it had Panax Ginseng in it. I figured it could have been that. But who knows.