The EEG (electroencephalogram) measures brain waves of different frequencies within the brain. Electrodes are placed on specific sites on the scalp to detect and record the electrical impulses within the brain. A frequency is the number of times a wave repeats itself within a second; this is sometimes referred to as “cycles per second” or Hertz. If any of these frequencies are deficient or excessive our mental performance can suffer.
Delta (0.1- 4 Hz): The lowest frequencies are Delta. These are less than 4 Hertz (Hz) and occur in deep sleep. Delta waves are important for renewal, rejuvenation and healing. Delta is the best state for immune system function, restoration and health. Delta waves are found in experiences of “empathy,” are involved in our ability to integrate and let go. Delta allows us to access information in our unconscious mind. Peak performers decrease Delta frequencies when high focus and peak performance is required.
Most individuals diagnosed with ADD (Attention Deficit Disorder) naturally increase rather than decrease Delta activity when trying to focus. This inappropriate response severely restricts the ability to focus and maintain attention. It is as though the brain is locked into a perpetual drowsy state.
Theta (4-8 Hz): Theta, in a properly functioning state, is seen in connection with creativity, intuition, and daydreaming. It is a repository for memories, emotions, sensations. Theta waves are strong during internal focus, meditation, prayer and spiritual awareness. It reflects the state between wakefulness and sleep; relates to the subconscious.
Theta is observed in anxiety, behavioural activation, and behavioural inhibition. When Theta functions within normal frequency, it mediates and promotes adaptive, complex behaviors such as learning and memory. Under unusual emotional circumstances, such as stress or disease states, one may feel distracted, unfocused.
Alpha (7-13 Hz): Good, healthy alpha brainwaves promote mental resourcefulness, aids in the ability to coordinate mentally, enhances overall sense of relaxation and/or fatigue. When Alpha predominates, most people feel at ease and calm. It is the major rhythm seen in normal relaxed adults. Alpha is a preferred state for the brain and occurs whenever a person is alert.but not actively processing information. It is in this state that one can move quickly and efficiently to accomplish whatever task is at hand, to switch quickly and easily from one task to another. Alpha is one of the most important frequencies for learning and using information taught in the classroom and on the job. Within normal ranges, we tend to experience good moods, see the world truthfully, and have a sense of calmness.
Beta (13-40 Hz): Beta activity is fast activity. It is the dominant rhythm in those who are alert or anxious; beta is the state that most of the brain is in when we have our eyes open and are listening and thinking during analytical problem-solving, judgement, decision making, processing information about the world around us. It may be absent or reduced in areas of cortical damage.
Low Beta (13-15 Hz – formerly SMR “sensorimotor rhythm”) can reflect ADD, lack of focused attention.
Mid-range beta (15-18 Hz) reflects thinking, awareness of self and surroundings, mental activity, alertness, active but not agitated.
High beta (above 18 Hz) can reflect alertness or agitation; mental activity such as calculating math or planning; general activation of mind and body functions.
Dysfunctional ranges of beta are associated with anxiety, nervousness and depression, worry, stress, paranoia, fear, irritability, moodiness, anger; also associated with weakened health and immune system.