Psychology. New York: Worth Publishers, 1995: 115. "Brain waves have been grouped according to their frequencies and labeled with Greek letters. Their most common frequencies include alpha, beta, delta, and theta."
alpha 8–12 Hz
beta > 13 Hz
delta 3 Hz
theta 4–7 Hz
"The Brain & the Mind." Psychology Volume 1. 2002: 117. "Delta waves occur mainly in infants, sleeping adults or adults with brain tumors. Theta waves occur mainly in children ages 2–5 years old. Alpha waves occur in adults who have their eyes closed or who are relaxed. Beta waves mainly occur in adults who are awake, alert or focused."
alpha 8–13 Hz
beta 13 Hz
delta 1–3 Hz
theta 4–7 Hz
"The Brain & the Mind." Psychology Volume 2. 2002: 97. "Hans Berger made many discoveries from the EEG recording and he found that the brain oscillate at about 10 cycles per second when the eyes are closed and relaxed and he called them alpha waves."
alpha 10 Hz
Webster's Third New International Dictionary. Merriam Company, 1981: 909. "Rhythmic fluctuations of voltage between parts of the brain resulting in the flow of an electric current, that has a pulsation frequency of 10 or more per second." > 10 Hz
Theory Behind BrainWave Generator. Noromaa Solutions Oy, 2003.
State Frequency range State of mind
Delta 0.5Hz - 4Hz Deep sleep
Theta 4Hz - 8Hz Drowsiness (also first stage of sleep)
Alpha 8Hz - 14Hz Relaxed but alert
Beta 14Hz - 30Hz Highly alert and focused
alpha 0.5–4 Hz
beta 14–30 Hz
delta 0.5–4 Hz
theta 4–8 Hz
Ever wonder what's going on up there in your brain at different states? Ever ponder about the brain wave frequencies when you're asleep, tired, relaxed, or energetic? Well, brain wave frequencies are categorized in 4 states: alpha, beta, delta, and theta.
Alpha waves occur when a person is relaxed, but alert, having a frequency of 8–13 Hz. During this state, a person is awake but resting. During sleep, alpha waves are replaced by beta waves.
The state of being focused, alert, or engaged in any form of activity are related to beta waves and they have a frequency of 14–30 Hz.
After a really long day, all a person desires is to fall into a deep sleep. Delta waves are associated with deep sleep. Their frequencies range from 0.5–4 Hz. Delta waves are known for triggering the release of growth hormone, which provides healing, hence the reason why sleep is so important during the healing process.
Theta waves have a frequency of 4–8 Hz and they occur mainly in children during the early stages of sleep, or in adults when they are emotionally stressed.
Samantha Charles -- 2004