Where can I buy fiber optic threads to use for textiles?

I would like to buy small bundles of fiber optic threads. I recently saw a girl using some at a concert so I know they must exist - a few strands of clear fiber optic threads with white LED woven into her hair, with a very small LED light source. I thought I might try weaving something like that in with cotton or hemp to make small glowing bracelets, but I have been able to find no vendors of simple fiber optic threads with LED sources online.