Yoga practices have long been associated with improvements in mental function. The ways in which the brain actually responds to postures, breathing and meditation, are slowly being discovered. In 2014, researchers at the University of Illinois sought to compile primary scientific literature aimed at elucidating the underlying mechanisms. A year later, their review was published in the journal: Complementary Therapies in Clinical Practice. Now, I wish to do my part by summarizing the key findings therein, which include waveform, psychological and physiological results.
There are five types of waves which brain experts like to study using an electroencephalogram (EEG). The list below highlights a few differences:
- Delta Waves: 0.5-3.9 Hz | Deep Sleep
- Theta Waves: 4-7 Hz | Effortlessness of Action
- Alpha Waves: 8-13 Hz | Relaxation
- Beta Waves: 12-39 Hz | Memory / Learning
- Gamma Waves: 40-100 Hz | Concentration / Attention
All yoga activities strengthen one or more of these wave forms. What is interesting is that certain activities target precise frequencies. These effects also appears to differ depending on whether the practitioner was a beginner, intermediate, or highly experienced at yoga. The authors pose a few interesting theories:
- Physical yoga has been shown to increase in both alpha and beta waves. Afterwards, the beta and theta waves were most pronounced.
- Breath retention techniques are highly associated with gamma waves, yet these brainwaves essentially disappeared after practice or were replaced by beta waves.
- Alternate nostril breathing was strongly associated with beta wave propagation.
- Kriya yoga practitioners demonstrate a gradual increase in alpha and theta wave amplitudes over a 30 day period. These changes were most apparent in the parietal lobe (governs sensation and movement).
- Meditation substantially increases in both alpha and beta waves.
The psychological and physiological finding of the report were also convincing. Participants who preformed left nostril breathing had significant improvements on spacial awareness exercises. By contrast, right nostril and alternate nostril participants showed improvements primarily in language tasks. Measurable differences in brain anatomy were also reported among asana and pranayama practitioners. PET scan imaging shown that Iyengar practitioners have increase blood flow to the pre-frontal context while decreased flow to the amygdala. The overall effect would be one of increased mental clarity with decreases in fear-based impulses. Those who preformed pranayama saw increases in hippocampus and insular cortex densities. These areas are responsible for our working memory and awareness, respectively. As the data mounts, yoga therapists will be able to customize uniquely tailored practice routines like never before!
For more information, please see:
Desai R, Tailor A, and Bhatt T. Effects of yoga on brain waves and structural activation: A review. Complement Ther Clin Pract, 2015 May; 21(2):112-8.
EEG and Meditation/Yoga. KalpaTaru. Available from: http://eegmeditation.eu/en/eeg-guided-meditation/eeg-and-meditation-yoga