Consciousness is the awareness we have of ourselves and our environment. Different states of consciousness are associated with different patterns of brain waves. Brain waves are tracings of electrical activity that is going on in the brain. Scientists record brain waves using an electroencephalograph (EEG), which monitors electrical activity through electrodes placed on the scalp. There are four main types of brain waves: alpha, beta, theta, and delta.

Type of Brain WaveCorresponding Mental State
AlphaVery relaxed or meditating
BetaAwake and alert
ThetaLightly asleep
DeltaDeeply asleep

Popular pages: States of Consciousness