The electrical activity of the brain has been

observed and classified with EEG (electroencephalograph)

equipment; signals picked up from the scalp by electrodes,

then filtered and amplified, drive a graph recorder. Brain

activity has been found to produce specific ranges for

certain basic states of consciousness, as indicated in ‘hz’

(hertz, or cycles/vibrations per second):

delta — 0.2 to 3.5 hz (deep sleep, trance state),

theta — 3.5 to 7.5 hz (day dreaming, memory),

alpha — 7.5 to 13 hz (tranquility, heightened

awareness, meditation),

beta — 13 to 28 hz (tension, ‘normal’


As you can see, some form of physical relaxation is implied

in the alpha, theta, and delta consciousness. These states

are in fact reached through deep breathing, hypnosis, and

other relaxation techniques. OOBE occurs during these

states, and delta is probably the most important for it.

The problem is really, as we have said, one of maintaining

mental awareness and alertness while experienceing these

altered states. Experimental subjects hooked to an EEG do

not show a discrete change from drowsy to sleep; it is very


At the threshold between sleep and waking

consciousness is a drowsy condition known as the hypnogogic

state. OOBE seems to occur during this state, or a

variant of it. By careful control of the hypnogogic state

(not going beyond it) it is possible to enter OOBE directly.