单项选择题

What is the main idea of the passage

A.There is little danger of serious after-effects when human beings are deprived of sleep for long periods of time.
B.Going without sleep for a long period will cause bad shortlivede ffects, but apparently no serious after-effects.
C.After 200 hours without sleep Tripp was suffering from "mental ill ness".
D.The doctors predicted Tripp would sleep for twenty or thirty hours.