The current human mind is bound to the body and thus to the brain. Brainwaves - or better scalp-waves - represent an important regulator of the human psyche.
Even if neurosciences and behavioral psychology work together, they do not throw enough light on the subjective experience, since both disciplines are predominantly based on the objective perspective of the third person.
The human brain produces waves of different frequencies in the various sleep phases. The neurologist and psychiatrist Hans Berger (1873-1941) is the discoverer of the electromagnetic "brain signals". The EEG (electroencephalogram) known from medicine is traced back to him.
The medicine therefore differentiates several waves of the 'brain'(scalp):
Delta waves are in the frequency range from 1 to 4 Hertz and occur in deep sleep, which is irreplaceable for the regeneration of the body, the immune system and the cells as well as for the mental balance.
Theta waves from the range of 4 to 8 Hertz occur in a state of deepest relaxation or in certain meditations. Daydreams - in dangerous form also known as short "mental absence" during motorway trips - are eg. unwanted phases of theta wave. Their use and / or production can improve the memory and concentration capacity or the learning ability in the long term.
Alpha waves are in the range of 8 to 13 Hertz. They occur in states of slight relaxation.
Beta waves from the range from 13 to 30 Hertz represent the brain waves of the normal wake state or of excited situations. Slight stress and anxiety situations can also lead to beta waves
They exists in the range over 30 Hertz and occur during strong concentration, during learning processes and meditation. They were measured among advanced monks of Vajrayana.
Even esoteric exercises can lead to a change in the brain waves. Professor Stephan Palos describes in his book "Breath and Meditation" changes in brainwave activity during the test of Chinese breath exercises.
Biofeedback : The biofeedback was modern for a time and allows controlled deep relaxation .
Also a stimulation by electro-acupuncture can be successful.
Muskelstimulatoren : Per Reizstrommuster werden Muskeln entspannt. Diese Geräte erzeugen je nach Hersteller kurzfristige Impulse hoher Spannung und sind evtl. auf lange Zeit nicht ganz unbedenklich.
Tens devices (0-120Hz / 0-130 mA / one-sided pulses): Their effect is supposedly based on a nerve stimulation. Due to the high impulse currents, they are also not entirely harmless (depending on the design).
Bloodzapper (3.92 Hz / Ik = 3mA / alternating rectangle). It was built by a Mr. Beck, distributed free of charge and has been rebuilt in a different forms. In the US, the device has also been clinically tested.
In principle, it is a simple low-current square wave generator with current limiting to a few milliampers, which stimulates muscles and weakens bacteria and viruses (US patent) and works very gently because of the small currents and the low frequency. The original device provides alternating rectangles and had hand electrodes. Possibly, it also has an effect in the direction of electroacupuncture.