Meridians are the channels through which according to Traditional Chinese Medicine ([wiki: TCM]) the Qi flows in our body.

I just read a [http://www.br-online.de/umwelt-gesundheit/artikel/0507/21-meridiane-biophotonen/index.xml?theme=print|german article] dating July 2005 stating that a german scientist prooved this. Then I googled a bit and found out there is an article in a magazine dating May 2003 about the same topic. Pretty interesting.

Article from 2003:
Biophoton emission of human body, S Cohen & F A Popp, Indian Journal of Experimental Biology, Volume 41 Number 5, May 2003