alpha wave
n.
A pattern of smooth, regular electrical oscillations in the human brain that occur when a person is awake and relaxed. As recorded by the electroencephalograph, alpha waves have a frequency of 8 to 13 hertz. Also called alpha rhythm.

[TahlilGaran] American Dictionary ▲

alpha wave
n. A brain wave, 8-12 cycles per second, associated with a state of relaxation and meditation and, hence, free of anxieties.
Try to produce some alpha waves; you will instantly feel a lot better.

[TahlilGaran] English Idioms Dictionary ▲