Question

Delta brain waves occur when you are

sleeping deeply.
daydreaming.
meditating.
concentrating.

Answer 1

It is A. sleeping deeply.

Delta waves, like other brain waves, are recorded with an electroencephalogram (EEG) and are usually associated with the deep stage 3 of NREM sleep, also known as slow-wave sleep (SWS), and aid in characterizing the depth of sleep.