Complete this summary using the words from the article.

(Hoàn thành bài tóm tắt sử dụng từ từ đoạn văn)

Sleep is good for physical and (1) _mental health. It helps stop (2)____ and keeps us healthy. We also study and work ___when we sleep for (4)___ hours. But in the twenty-first century, we aren't getting enough sleep. One reason is that we stay up (5)____or_(6)___all night. Another reason is that (7)____ light from screens keeps us awake. As a result, medical experts advise us to stop looking at screens (8)____ hour before bed.