Hello Giancarlo,
I know that people have different experiences with the same herbal (or even pharmaceutical drug), but for me the way to go is Ginseng. I have been taking it every single day now for the last 5 years, and it boosts my alertness, concentration, and memory, as well as took away my heartburn completely. I was surprised that you did not list ginseng along with your list of the 'popular' herbals. Anyway, ginseng has helped me stay awake and productive for 4 hours of night school right after working a full 8 hour days at work (3 nights a week.)
