What does the word “sleep” mean?

Reading Comprehension 
Read the quoted parts carefully and answer the questions in English."The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep."
What does the word “sleep” mean?
【正确答案】：

“SLEEP” HERE INDICATES TO HAVE HIS LAST REST OR TO DIE. 

【题目解析】：诗人停在林子边陷入沉思，幻想中的诗人可以抛弃掉尘世的责任与义务，烦恼与不幸，无拘无束驰骋在幻想世界中，不理凡尘俗事。可是若任由幻想中的自我去响应那彼岸世界的呼唤，诗人会选择就此安息。这一段是诗歌最后一小节，尽管树林可爱、幽暗而深远，在雪夜中令人流连忘返，可还未到就此停住的时候，还有尘世的责任与义务，生活的夙愿未完，不能任凭自己沉浸在幻想中。所以这里的“sleep”指的是“死亡”。