Read and Complete

Choose the word that best completes each blank.

Sleep is not wasted time. While we rest, the brain sorts through the day's events and decides what to keep. Memories that seem important are strengthened, while unimportant details fade. Studies show that people who sleep after learning something new remember it far better than those who stay awake. This is one reason experts warn students against staying up all night before an exam: losing sleep can erase the very facts they tried to study.

During sleep the brain —strengthensdeletesignores important memories while weak details fade, which is why students who skip sleep before a test often —rememberforgetstudy less than those who rest.