I’ve experienced all sorts of internal effects, ranging from feeling “high” to losing all awareness of my body, to seriously feeling like my head was turned completely backwards, only to just have to open my eyes to find it facing straight forward where I left it, to drifting into transcendent states of mind that can hardly even be described with words.
Stress: In one randomized controlled trial with 108 participants, a single session of alpha and delta stimulation resulted in significantly less anxiety in surgical patients. Another session of theta stimulation resulted in improvement in certain measures of stress. Stimulation with certain frequencies of alpha and beta were reported to provide the most significant benefit for those who are stressed.
The activity of neurons generate electric currents; and the synchronous action of neural ensembles in the cerebral cortex, comprising large numbers of neurons, produce macroscopic oscillations. These phenomena can be monitored and graphically documented by an electroencephalogram (EEG). The electroencephalographic representations of those oscillations are typically denoted by the term 'brainwaves' in common parlance.