Brain waves are electrical pulses produced by the brain that operate at different speeds. They can be detected by electroencephalography (EEG) scans and are often classified by their frequency range using Greek numerals! Here are the different types of brain waves & their effects: * Delta 0-4 Hz: sleep * Theta 4-8 Hz: Deeply relaxed state | can occur during sleep, ‘day dreaming’ & meditation * Alpha 8-13 Hz: Relaxed & healing conscious state * Beta 13-20 Hz: Alertness | Concentration | Cognition