The Four Types of Brain Waves (EEG)

Alpha waves (9-14 Hz)-When you are truly relaxed, your brain activity slows from the rapid patterns of beta into the more gentle waves of alpha. Fresh creative energy begins to flow, fears vanish and you experience a liberating sense of peace and well-being. The "alpha state" is where meditation starts and you begin to access the wealth of creativity that lies just below our conscious awareness. It is the gateway that leads into deeper states of consciousness.

Theta waves (4-8 Hz)-Going deeper into relaxation and meditation, you enter the "theta state" where brain activity slows almost to the point of sleep. Theta brings forward heightened receptivity, flashes of dreamlike imagery, inspiration, and, sometimes, your long-forgotten memories. It can also give you a sensation of "floating".

Theta is one of the more elusive and extraordinary realms we can explore. It is also known as the twilight state which we normally only experience fleetingly as we rise up out of the depths of delta upon waking, or drifting off to sleep. In theta, we are in a waking dream, and we are receptive to information beyond our normal conscious awareness. Many believe that theta meditation awakens intuition and other extrasensory perception skills.

Delta waves (1-3 Hz). This slowest of brainwave activity is found during deep, dreamless sleep. It is also sometimes found in very experienced meditators.

Rhythmic slow activity in wakefulness is common in young children, but is abnormal in adults. In addition to the above types of rhythmic activity, individual transient waveforms such as sharp waves, spikes, spike-and-wave complexes occur in epilepsy, and other types of transients occur during sleep.

In the transition from wakefulness, through Stage I sleep (drowsiness), Stage II (light) sleep, to Stage III and IV (deep) sleep, first the alpha becomes intermittent and attenuated, then disappears. Stage II sleep is marked by brief bursts of highly rhythmic beta activity (sleep spindles) and K complexes (transient slow waves associated with spindles, often triggered by an auditory stimulus). Stage III and IV are characterized by slow wave activity. After a period of deep sleep, the sleeper cycles back to stage II sleep and/or rapid eye movement (REM) sleep, associated with dreaming. These cycles may occur many times during the night.