听力原文:W: Doctor, I haven't been able to get enough sleep lately, and I'm too tired to concentrate in class. M: Well, you know, spending too much time indoors with all that artificial lighting can do that to you. Your body loses track of whether it's day or night. Q: What does the man imply? (13)
A.
The woman is making too big a fuss about her condition.
B.
Fatigue is a typical symptom of lack of exercise.
C.
The woman should spend more time outdoors.
D.
People tend to work longer hours with artificial lighting.