EEG Brain Rhythms

Simulated electroencephalographic oscillations across frequency bands

Delta (0.5–4 Hz) — deep sleep
Theta (4–8 Hz) — drowsiness
Alpha (8–13 Hz) — relaxed
Beta (13–30 Hz) — alert
Gamma (30–80 Hz) — cognitive

EEG records the summed electrical activity of millions of cortical neurons. Different mental states produce characteristic frequency mixtures: slow delta waves dominate deep sleep, alpha emerges at rest with eyes closed, and fast gamma oscillations (Whittaker/Singer 40 Hz hypothesis) correlate with conscious binding and feature integration.