I've done it many times there's a really good place nearby.
I would go once a week if I could . You can get into a very deep
space doing this but I've found it takes a little practice . You realize
pretty quickly how cluttered and noisy the mind is and how it can be
difficult to quiet your thoughts at times . I try to go for the longest session
I can because it takes me a while to relax and calm my thoughts down.
I think it's the deepest you can without any drugs in fact in my opinion
It doesn't really need anything added to it . It really stands alone and has huge
potential for exploring the mind and actually making positive lasting changes in your life.
The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
Arthur C. Clarke
http://vimeo.com/32001208