The brain generates weak electrical impulses representative of its particular activities. As recorded by the electro-encephalograph (EEG), they fall into particular levels assigned Greek letters. Beta, at 14-26 cycles per second, is our normal waking state including focused attention, concentration, thinking, etc. Alpha, 8 to 13 cycles, is the next level down characteristic of relaxation, alert receptivity, meditation and access to the subconscious mind. It is at 8 cycles per second, the border between alpha and theta that Trance occurs. Theta, 4 to 7, is lower yet and occurs just before (hypnopompic) or after (hypnagogic) sleep and is characteristic of light sleep, deep meditation, vivid imagery, and high levels of inner awareness. Delta, 0.5 to 3, is characteristic of deep sleep.