Low Beta (16 - 18 Hz) is thought of as ‘fast idle’ or musing thought. Beta (18 - 22 Hz) equates with high engagement and active thinking. High Beta (22-30 Hz) corresponds to highly complex thought, the integration of new experiences, and excitement. Beta waves are generally dominant in a highly engaged mind; however, too much beta activity can result in difficulty relaxing, anxiety and insomnia.
Alpha (8-15 Hz): Often recognized as the resting state of the mind, alpha waves are dominant during wakeful relaxation (physical and mental) and certain states of meditation. They are tied to good moods and calm.
Theta (4-7 Hz): Theta brain waves can be considered the subconscious; they reflect the part of our mind that lies between the conscious and the unconscious and that retains memories and feelings. Theta waves have connections with daydreaming and the experience of waking up or drifting off to sleep. Theta waves are prevalent during meditation, prayer, and spiritual awareness and are associated with intuitive thinking and creativity. An excess of theta activity in the left hemisphere of the brain is thought to cause disorganized thinking, whereas a surplus in the right hemisphere can result in impulsivity.
Delta (0.1-3 Hz): Delta waves generally occur in deep meditation and during deep dreamless sleep. Parkinson's disease, schizophrenia, and narcolepsy are all characterized by changes in delta wave activity.