The overlap of the SR with human brain waves (alpha/theta)

The fundamental mode of the Schumann resonance (≈ 7.83 Hz) lies in frequency within the range of human brain waves — at the boundary of the theta (4-8 Hz) and alpha (8-12 Hz) bands. This numerical overlap is, in popular literature, the most frequent argument for a "connection of humans with the Earth".

It must, however, be emphasized that this is a factual coincidence of two independent phenomena. Brain waves are the collective electrical activity of neurons; the SR is the resonance of a global electromagnetic cavity excited by lightning. The fact that both quantities "fall" into the same band of single-digit hertz is due to the fact that both independently lie in the region of very low frequencies. The claim of a "synchronization of the brain with the Earth" or that the brain "tunes" to the SR is not proven causality — there is no robust mechanism nor replicated experimental evidence. The match of frequency bands should therefore be taken as a starting point for a hypothesis, not as proof of an effect.