What is Brainwave Rhythms?#
The brainwaves are divided into five kinds of rhythms based on their frequencies. They are α wave, β wave, θ wave, δ wave, and γ wave. When your brain is in different states, the percentage changes. Through frequency domain analysis of real-time brainwaves, we'll know the power ratio of each brainwave. The change in their percentage reflects the change of brain states.
The power ratio of each brainwave frequency #
| Name | Frequency | Power Ratio | Brain state | Meditation state |
|---|---|---|---|---|
| Gamma wave (γ) | 30-45Hz | About 2% | Aware and focused | Experienced meditators do meditation. |
| Beta wave (β) | 14-30Hz | 35~55% | Focused, active and intense | When you are highly focused during meditation. |
| Alpha wave (α) | 8-14Hz | 15~35% | Aware and relaxed with eyes closed | It increases when you close eye and feel relaxed. |
| Theta wave (θ) | 4-7Hz | 25~45% | Deeply relaxed, or in light sleep | Experienced meditators may have a strong theta wave but keep awake. |
| Delta wave (δ) | 1-3Hz | About 5% | Deep sleep | Change very little during meditation. |
note
There are slight discrepancies in the frequency bands of the brainwave rhythm reported on different papers. The frequency band adopted in our algorithm is based on below.1
Besides, the ratio varies from person to person, related to gender and age, etc.234
Following is a typical case from a young man at the age of 28 when he was awake with his eyes open: β waves are dominant (30%-40%), θ waves the second (25-35%), α waves the third (20%-30%), γ waves the fourth (around 10%) and δ waves the last (below 10%).
note
The ratio may be different from the result made through the clinic or other devices as the data profoundly depends on the device's sensitivity to the frequency and the sensor placement.
- Sanei, Saeid & Chambers, Jonathon. (2007). EEG signal processing. 10.1002/9780470511923.↩
- Doppelmayr, Michael. (2004). Changes in EEG-bandpower and coherence in the theta, alpha, and gamma band while solving Raven's Matrices. International Journal of Psychophysiology. 54. 38-38. ↩
- Otero GA, Pliego-Rivero FB, Fernández T, Ricardo J (2003) EEG development in children with sociocultural disadvantages: a follow-up study. Clin Neurophysiol 114:1918–1925. ↩
- Latta F, Leproult R, Tasali E, Hofmann E, Van Cauter E (2005) Sex differences in delta and alpha EEG activities in healthy older adults. Sleep 28:1525–1534.↩