Recently I have been experimenting with automatic drawing. Surrealist automatism is a technique developed by psychics and championed by the Surrealists, later adopted by Picasso and Miro, where you put aside rational control and allow your subconscious to take the pen.
I tend to either close my eyes or work in a dark room, grounding myself with my feet on the floor and hands on the desk; I focus on my breathing and try to quieten my conscious mind. My hand moves freely across the paper in a continuous line - I do not lift the pen until the drawing feels complete.
So far I can observe differences in mood - with flowing lyrical lines depicting relaxed and calm states, and jagged angles suggesting tension and overload. Depending on what I have been working on during the day, images or patterns might rise up.
I find nighttime is best for automatic drawing, as my conscious mind is tired and quietened, and my unconscious is waiting in the wings to take over. Yielding rational control allows my suppressed unconscious a voice. Automatic drawing is a practice which should be developed over a period of years.
Jungian psychology has a big influence on my approach - I sometimes think of the Thames as the collective unconscious of London, all the submerged discarded fragments rolling away in the tides.