Sleep stages are defined in terms of the
a. amount of time spent sleeping
b. length of restful sleep experienced
c. occurrence of brainwave patterns
d. number of dreams experienced

Correct answer choice is:

C. Occurrence of brainwave patterns.

Explanation:

During sleep, the body goes into five distinct stages of both REM (rapid eye movement) and NREM (non-rapid eye movement) sleep. Overhead the passage of the darkness, the body will go into this five-stage sequence four to six intervals, employing an aggregate of 90 minutes in a particular stage.