TThe human brain produces electrical activity in waves that can be measured using a device called an electroencephalograph (EEG). By studying EEG results, scientists can identify different types of brain waves. The main types when we are awake are: • Alpha waves (medium speed): appear when we are relaxed and not actively thinking or interacting with the environment. • Beta waves (fast): appear when we are concentrating, solving problems, or interacting with our surroundings. • Theta waves (slow): appear during drowsiness, daydreaming, or light sleep. They can also show up during restless, unfocused thinking. (A fourth type, delta waves, occurs during deep sleep.) Neurofeedback, also called EEG biofeedback or neurotherapy, is a technique used to train the brain. It is often applied in people with ADHD, because research shows that many individuals with ADHD have too many theta waves and too few beta waves in the frontal areas of the brain. This can result in low arousal, poor attention, and hyperactive or impulsive behavior.