Kanji Dyslexia

I've decided that I must be kanji dyslexic. (kanji= Japanese characters) I had to write my address on an envelope tonight in the Japanese sytle, which is vertical rather than horizontal. Needless to say, I wrote mirror images of some characters, had to really, really think about how to write other characters and basically wrote crap unbalanced characters in general. Why is it so much harder to write vertically than horizontally? It boggles my mind as to why it is so difficult to write in a different direction.