B. Listen to a talk about sleep. Take notes and complete the following summary. Everyone needs to 1 . It seems that there are 2 purposes of sleep: 3 rest and 4 or 5 rest. We need to rest our 6 and our 7 . Each night we 8 between two kinds of sleep: 9 sleep and 10 sleep. In passive sleep, the 11 is at rest. The 12 slows down. The body processes become very 13 . This stage of sleep is known as 14 sleep because the brain 15 move in a very 16 . If a person continues to sleep, she or he enters a new stage, a more 17 stage. The brain 18 rises, the amount of 19 in the brain increases, the body becomes very 20 , and the brain goes from being very 21 to being 22 . And the eyes begin to 23 rapidly. This is a 24 that the person is 25 . Throughout the night, people 26 between 27 and 28 sleep. This 29 is repeated 30 times throughout the 31 . During 32 hours of sleep people 33 for a total of 34 , on the average. We need passive sleep in order to 35 . We need active sleep in order to 36. And dreaming helps us to 37.