Greg is hooked up to an eeg and his brain is producing smooth waves at a rate of about 10 per second. greg is most likely:

awake and relaxed with their eyes closed. The frequency of 10 Hz is right in the middle of the alpha band of 7.5 to 12.5 Hz. Alpha waves are generally detected if the subject is awake and relaxed with their eyes closed. They drop in amplitude when the subject opens their eyes.