[单项选择]For millions of years before the appearance of the electric light, shift work, all-night cable TV and the Internet, Earth’ s creatures evolved on a planet with predictable and reassuring 24 - hour rhythms. Our biological clocks are set for this daily cycle. Simply put, our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives. ( Contrary to popular belief, humans don’ t need less sleep as they age. )
But on average, Americans sleep only about seven and a half hours per night, a marked drop from the nine hours day averaged in 1910. what’s worse ,nearly one third of all Americans get less than six hours of sleep on a typical Work night. For most people, that’ s not nearly enough.
Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep disorders. Some sleeping disorders are generic. But ma
A. Most people need less sleep when grow older.
B. Most people need seven and a half hours of sleep every night.
C. On average, people in the U. S. today sleep less per night than they used to.
D. For most people, less than six hours of sleep on a typical work night is enoug

[单项选择]For millions of years before the appearance of the electric light, shift work, allnight cable TV and the Internet, Earth’s creatures evolved on a planet with predictable and reassuring 24-hour rhythms. Our biological clocks are set for this daily cycle. Simply put, our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives. (Contrary to popular belief, humans don’t need less sleep as they age.)
But on average, Americans sleep only about seven and a half hours per night, a marked drop from the nine hours they averaged in 1910. What’s worse, nearly one third of all Americans get less than six hours of sleep on a typical work night. For most people, that’s not nearly enough.
Finding ways to get more and better Sleep can be a challenge. Scientists have identified more than 80 different sleep disorders. Some sleeping disorders are genetic. But many prob
A. Most people need less sleep when they grow older.
B. Most people need seven and a half hours of sleep every night.
C. On average, people in the U.S. today sleep less per night than they used to.
D. For most people, less than six hours of sleep on a typical work night is enoug

[单项选择]

Sleep

For millions of years before the appearance of the electric light, shift work, all-night cable TV and the Internet, Earth’s creatures evolved on a planet with predictable and reassuring 24-hour rhythms. Our biological clocks are set for this daily cycle. Simply put, our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives. (Contrary to popular belief, humans don’t need less sleep as they age.)
But in average, Americans sleep only about seven and a half hours per night, a marked drop from the nine hours they averaged in 1910. What’s worse, nearly one third of all Americans get less than six hours of sleep on a typical work night. For most people, that’s not nearly enough.
Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep
A. Most people need less sleep when they grow older.
B. Most people need seven and a half hours of sleep every night.
C. On average, people in the U. S today sleep less per night than they used to.
D. For most people, less than six hours of sleep on a typical work night is enough.