A mole rat researcher hopped onto Google Earth to examine the patterns in which tents were pitched on campgrounds. He discovered that tents are hard to see on Google Earth; and herds of cattle much easier. 
He was careful to point out that: 1) correlation does not equal causation; and 2) an experiment of sufficient scale as to provide conclusive proof would be basically impossible. He also noted that this topic is a juicy one for further study and experimentation:
“The biological significance of the shown magnetic alignment remains enigmatic. It has been speculated that maintaining a symmetric position to the field lines somehow influences certain physiological processes (ref. 2 and references therein). Indeed, in humans the rapid eye movement latency is shortened in the E-W position of sleepers compared with the N-S position (20), and statistically significant differences in the EEG of normal subjects have been found, depending on whether the subjects sit facing the N-S or E-W direction (21). Maintaining a certain magnetic direction may provide also a constant directional reference for spatial orientation, which might be useful e.g., after disturbance and fast escape. Noteworthy, all of the studied ruminants are social animals, with large home ranges, moving over large distances, originally in habitats (dense forests or grassland) without apparent landmarks. Our results call for an in-depth study of this phenomenon and challenge neuroscientists, biochemists, and physicists to study the proximate mechanisms and biological significance of magnetic alignment. It is amazing that this ubiquitous conspicuous phenomenon apparently has remained unnoticed by herdsmen and hunters for thousands of years.”
A broader sample size that looked at additional factors like weather conditions and herd size:
https://www.pnas.org/doi/10.1073/pnas.0803650105
I stopped riding over a year ago because I’m a mess from POTS-type symptoms that the doctors say are likely related to my significant (Stage III+ or IV) TMD. Personally, I would welcome more research into the differences on the EEG scans cited in the link above. Not because I believe that I’m out of magnetic alignment, but because such research could lead to a better understanding of how and why jaw problems cause the vascular system to short circuit and eventually to better treatments.
