Typical Brain Waves and Deviations

Human brainwave frequencies range from 0.5 – 135 Hz. Combinations of these frequencies are always present in various amplitudes and symmetries, with a dominant “leader” frequency or frequency band that is considered normal for each state. Deviation from the normal frequency can cause problems and disorders. Achieving equilibrium between the brainwaves in the right and left side of the brain (inter-hemispherical symmetry) is also important for the brain to function properly.) Natural brain frequencies are as follows: alpha: 8-12 Hz; beta, 12-30; theta: 4.0-8.0 Hz; delta: 0.5-4.0 Hz, and gamma: 30 Hz and above.

​Reference Values:
Alpha: 8-12 Hz
Beta: 13-30 Hz
Theta: 4.0-8.0 Hz
Delta: 0.5-4.0 Hz
Gamma: above 30 Hz


The natural human brainwave frequencies for each band are shown below. These frequencies can be picked up by an EEG (Electroencephalogram) from the surface of the brain after amplification, as they are in the range of micro-volts (which are very low voltages, so low that they can only be seen after amplification by an EEG machine. A mixture of these frequencies is present at any given time.


Normal Brain Waves


Quantitative Electroencephalography (QEEG)/Brain Mapping is a procedure that processes the recorded EEG activity from a multi-electrode recording using a computer and converts it into a brain map showing different brainwaves. QEEG can combine signals from many areas of the brain and represent it in the shape of a map showing different features. For example, some maps show all the frequency bands in different parts of the brain, others show a single frequency band across the brain, while others show comparisons of the brain areas. This in-depth computerized analysis of the digital EEG can assist and even augment our understanding of the EEG and brain function as seen below:


There are several conditions that can lead to brain wave deviations, including:

• Hereditary
• Neurological
• Psychiatric
• Traumatic Brain Injury (TBI)
• Brain Tumors

Over recent years, scientific literature has begun to associate abnormalities of the brainwaves with a growing number of conditions, even to the extent that most recent literature has been able to use these brainwave abnormalities as biomarkers for certain conditions.
Brain WavesWhen certain areas of brain are in an over-arousal state, individuals can experience:

• Anxiety
• Nightmares and other sleep problems
• Impulsivity
• Aggression

Under-arousal of the brain is related to:

• Depression
• Chronic pain
• Insomnia

Unstable brainwaves are seen in:

• Obsessive-Convulsive Disorders (OCD)
• Epilepsy
• Panic Attacks

Gamma brain waves cause hyperactivity; and when there is excess of hyperactive brain waves, it can lead to:

• Schizophrenia
• Delusions
• Hallucinations

Electromagnetic therapy can change brain activity to help people who are experiencing symptoms of certain mental health conditions.
EEG Frequency Bands in Psychiatric Disorders: A Review of Resting State StudiesDeviations in frequency bands, from a normal population data-set, are presented across a spectrum of psychiatric disorders, including:

• Depression
• Attention deficit-hyperactivity disorder (ADHD)
• Autism
• Addiction
• Bipolar disorder
• Anxiety
• Panic disorder
• Post-traumatic stress disorder (PTSD)
• Obsessive compulsive disorder (OCD)
• Schizophrenia

Dominant results for each individual disorder and band. (A) Differences in absolute power for each disorder (relative to control) for eyes closed condition (top), eyes open (middle) and eyes open and closed combined (bottom). White boxes indicate no change, black indicates an increase, and gray indicates a decrease. Opposing results are shown by hashed boxes. (B) Difference in results between absolute power and relative power for the same disorders. White indicates no difference, gray indicates a significant increase or decrease in one but no significant difference in the other, while a hashed box indicates opposite results.

Changes of the brain’s bioelectrical activity in cognition, consciousness, and some mental disorders
The raw EEG and QEEG images show that slow brain waves are seen in conditions such as:

• Sleep
• Coma
• Brain death
• Depression
• Autism
• Brain tumors
• Obsessive–compulsive disorder (OCD)
• Attention deficit hyperactivity disorder (ADHD)
• Encephalitis

While rapid waves are generally reported in conditions like:

• Epilepsy
• Anxiety
• Post-Traumatic Stress Disorder (PTSD)
• Drug abuse

Unsurprisingly, research into these brainwave abnormalities has led to intervention procedures where, using neurofeedback and other methods, the brain is coaxed to bring abnormal frequencies to the normative state. This helps lessen symptoms associated with specific conditions. These modalities have been so successful in helping mitigate many conditions that in certain cases the dosage of drugs used for the condition can be reduced, minimizing associated adverse side-effects.
Pulsed Electromagnetic Field (PEMF) therapy is one example where, by application of very mild electromagnetic pulses in the desired frequency band, many conditions can be improved without accompanying adverse-effects that can occur with pharmacological therapy. With wearable neuro-tech now a reality, PEMF devices can be used anywhere and anytime for a nominal cost, whether you intend to use it as a stand-alone device for home use or in combination with other types of therapy.