"Silva Method helped me to be up during my 21h watch"

I was a troubled young sailor. The Method helped me during a cruise where I was working 7 hours on and 7 hours off. I would work a watch, stay up during the off watch and do the next watch, then shower and sleep (while I went to my level) during the next off watch. I was never tired during the 21 hours I was up. The other fellow would try to sleep during every off watch period and he was always tired. Over the years I have used the Method, but not as much as I should. I have a daughter who is now 17 and a senior in high school. I bought this mainly for her to help with her future.