Alpha is an interesting brainwave — really, the king of brainwaves. Alpha is the most obvious brainwave to spot with the naked eye — it has high amplitude and is often rhythmic. It was the first discovered and classified by Berger, as well as the first brainwave used in experimental self-regulation (later called EEG Biofeedback) by University of Chicago professor Joe Kamiya in 1959. Alpha is the first conscious brainwave and the bridge that links the unconscious brainwaves of theta and delta to the active thinking brainwaves of beta and gamma. Alpha is 9-12 Hz, a relaxed and focused space, responsible for the state of flow, being in the zone, and creating. You are often in alpha when you are watching TV, driving your car, or doing any “mindless activity". When we close our eyes, we signal to our body that we are in a position to relax and safely fall asleep. When we close our eyes, a normal response is an increase of 50% or more alpha in the back of the head.
The speed of your alpha brainwaves is your dominant or “peak” frequency. It is like the shutter speed of a camera. The faster your alpha peak frequency, the faster you are processing data and the more data you can, therefore, take in.
If Alpha brainwaves are high amplitude (big on they axis) the individual is often in a trace or an inattentive, daydreamy state. High amplitude alpha may mean that the individual uses a lot of THC, or may have attentional difficulties.
Alpha will attenuate, or "block," when we become mentally occupied. The brain will then begin to generate "beta" waves, ranging from 16-35 Hz.
Theta brainwaves run at 4-8 oscillations per second (4-8 Hz), and are the dominant brainwave in REM sleep, dreams, and hypnosis. This is the subconscious and the borderland to consciousness. Theta is a powerful state for learning in an uncritical fashion. Hypnotherapists will take clients to the cusp of theta and alpha (read: unconscious and conscious) because humans are highly suggestible in this space. Jung felt that dreams were signs referencing complex psychological, emotional, and transcendental realities. Dreams access the storehouse of memories in the limbic system (the amygdala and the hippocampus); our individual dreams are often of a collective reservoir, containing ancient and primitive themes and narratives common to the human experience. When we are in theta, our subconscious offers us images that are symbolic of those repressed or otherwise inaccessible memories and information.
Seeing small delta and theta waves in the waking, eyes open EEG is normal. However, excessive or large (high amplitude) delta and theta waves often signify neurological or developmental problems.