<h2>Brainwaves are measured patterns</h2><p>EEG records electrical activity from the scalp. Researchers often discuss activity in frequency bands such as delta, theta, alpha, beta and gamma.</p> <table><tr><th>Band</th><th>Common approximate range</th><th>Often discussed around</th></tr><tr><td>Delta</td><td>~0.5–4 Hz</td><td>Deep sleep</td></tr><tr><td>Theta</td><td>~4–8 Hz</td><td>Drowsiness, memory, meditation research</td></tr><tr><td>Alpha</td><td>~8–12 Hz</td><td>Relaxed wakefulness</td></tr><tr><td>Beta</td><td>~13–30 Hz</td><td>Active waking cognition</td></tr><tr><td>Gamma</td><td>~30 Hz and above</td><td>Higher-frequency neural coordination</td></tr></table> <p>Boundaries vary across research conventions. These labels describe frequency ranges; they are not five simple “modes” that determine a person's entire mental state.</p> <p>Deep dive: <a href="/theta-waves-guide.html">Theta Waves</a>.</p>

Brainwaves Explained: Delta, Theta, Alpha, Beta & Gamma

A practical map of common EEG frequency bands and why frequency labels need context.

Editorial version: September 2026