Register now for unlimited free access!

A valid email address. All emails from the system will be sent to this address. The email address is not made public and will only be used if you wish to receive a new password or wish to receive certain news or notifications by email.
Several special characters are allowed, including space, period (.), hyphen (-), apostrophe ('), underscore (_), and the @ sign.
Provide a password for the new account in both fields.
Back to top


A recording of the electrical activity of the brain by means of electrodes placed on the surface of the head. With the EMG and EOG, the EEG is one of the three basic variables used to score sleep stages and waking. Sleep recording in humans uses surface electrodes to record potential differences between brain regions and a neutral reference point, or simply between brain regions. Either the C3 or C4 (central region) placement according to the International 10-20 System is referentially (referred to an earlobe) recorded as the standard electrode derivation from which state scoring is done. EEG is also used to diagnose epilepsy and other brain diseases.


Definition reprinted with permission from Culebras, Antonio, Clinical Handbook of Sleep Disorders, Butterworth-Heinemann