Mark Is a Participant in a Sleep Study at His

Multiple Choice

 Mark is a participant in a sleep study at his university. The researchers observe that Mark enters REM sleep earlier in the night than most of their other participants, and he spends a greater than normal proportion of his sleep time in REM. They explain to Mark that

A) he should be evaluated at the student health center for depression.
B) his sleep is within normal ranges for a young adult.
C) he probably is working out too strenuously at the gym right before bedtime.
D) he probably should avoid taking so many morning courses, as he is likely to be an "owl."