정답은 3번이라고 되어 있어서 왜 4번은 정답에서 벗어나는지 궁금해서요..
부탁드립니다.☺ 다음 글의 주제로 알맞은 것은?
host: i have a kind of funny question. what happens if you don’t sleep for a long time?
dr. z: actually, i have the perfect example for you. once, an american high school student managed to stay awake for 264 hours, breaking the previous record of 260 hours. but he had some disturbing psychological problems along the way. he saw things that didn’t exist by the fourth day, and developed short-term memory problems.

① the causes of sleeping sickness
② the factors of disturbing sleep
③ the result of the want of sleep
④ the necessity of sufficient sleep
⑤ the first symptoms of insomnia