If you want to skip the misery （痛苦） that comes with fighting a seasonal cold or flu，a new research explains why sleep is some of the best preventive medicine．We already knew that not getting enough sleep can lead to an increased risk of getting sick，but Nathaniel Watson，a neurologist and sleep specialist at the University of Washington School of Medicine，said this new research helps explain why．
Sleeping poorly can block specific genetic processes in the cells that make up your immune system，which is responsible for fighting off infections and diseases，according to the new study．"Your immune system is not functioning the way it was meant to when you are deprived of sleep，"Watson said．This study is the first one that Watson and his colleagues are aware of that looks at what happens to the immune system's DNA when you're not getting adequate sleep．
The researchers followed 11 pairs of identical twins for the study．One twin reported sleeping at least seven hours per night，while the other slept approximately one hour less per night．Looking at identical twins helped control the fact that sleep needs vary by person，Watson explained．Genes account for about 50 percent of our sleep needs，meaning identical twins are the best-case scenario （方案） for getting a good comparison．
The researchers took blood samples at the end of the study，which revealed that the immune system of the twin who slept less was less active than the twin who slept more．Those who slept less were actually making fewer proteins，the molecules that our bodies run on．"They had an under-performing immune system，"Watson said of the shorter sleepers，"which would put them at higher risk of getting sick．"
To control other potential factors that could affect sleep need and immune health，the researchers excluded people from the study who had diabetes，depression or other mental health problems and sleep disorders．They also left out shift workers，smokers，drug users and drinkers．

（1）What do the underlined words in Paragraph 2 mean？

D

D

A．Change sleep pattern．
B．Benefit from sleep．
C．Have to sleep．
D．Lack sleep．
（2）Why did the researchers choose identical twins for the study？

B

B

A．To find participants more easily．
B．To make the results more accurate．
C．To make the study more interesting．
D．To show sleep needs vary by person．
（3）What does the author most probably want to show in the last paragraph？

B

B

A．Many factors can lead to sleep disorder．
B．The findings of the study can be reliable．
C．Poor sleep could lead to many problems．
D．The findings of the study remain to be tested．