What is the physiology of dreams and lucid dreams?
The electrical activity of the brain has been observed and classified with EEG (electroencephalograph) equipment; signals are picked up from the scalp by electrodes, then filtered and amplified to 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’ consciousness) In the drowsy state before falling asleep, the EEG is characterized by many alpha waves while the muscles start to relax. Gradually this state gives way to Stage 1 sleep. Three more stages follow, each having different EEG patterns and marked by successively deeper states of relaxation. By Stage 4 the sleeper is very relaxed, his breathing is slower, and skin resistance high. He is very hard t
