I would choose option E for this question.
A - Is exactly the opposite answer, which begs the doctors to suggest sleep deprivation. Clearly not the answer
B- Makes a comparison and suggests that it be difficult to keep awake when compared to a non-depressed person (Option shouts out of context)
C - The stimulus does not mention anything about prolonged sleep deprivation - Not an answer
D -The option does not refute sleep deprivation as a medication to depression, but suggests that the chemistry associated with the brain does not explain the link between sleep and wakefulness (It simply means the psychologists are not able to explain why sleep deprivation elevates a person from depression period)
E - This clearly explains why sleep deprivation is not recommended over conventional medication. Since sleep deprivation is only a respite cure and it tends to magnify the problem later (when the person goes to sleep). Sleep deprivation cannot be used as a cure.