Peppermint is very good for creating a focused mind.

When I was younger I used to use peppermint to study for exams and now when I need to concentrate. I've never used it before bed though as I worry that it would make me too alert to fall asleep - but then I boarder on insomnia. For a lot of people it would probably be very mild and work to help keep the mind more focused during dreams.
Interesting and def a lot tastier than some of the other lucid dreaming recommended teas!