T, Perhaps u are already familiar with Dr Becker's work and his books. If not, "The body electric" shares how the earths magnetic field and its cyclic changing is particulary affecting our mental/emotional stuff daily.
When test subjects were in a perfectly shielded from the magnetic field room, their systems, endocrine, dna reproduction ect, all lost regualrity, but if a 10 hz field at 0.025 volts was introduced, things returned to normal.
Also I think that is where i got the info on how untill researchers went low enough in voltage no affect was being seen in some of the dc studies being done over the last 60 years. Its a great book for all who are interested in the western Science studies of the magnetic fields in living things. The Body Electric by Robert Becker MD.