Delta waves are produced when your body is completely unconscious and asleep. This state of mind allows your body to heal itself due to extreme relaxation. These frequencies are the lowest that the brain produces. Optimal output of Delta waves means a well-rested night's sleep. High output of Delta waves could be correlated to low concentration, severe ADHD, learning problems, and possible brain injuries. Low output of Delta waves results in a poor night's sleep and lack of rejuvenation and revitalization.
0.1 – 3 Hz