Jet lag is caused because the bodyclock does not readjust immediately to the time change.
时差是因为生物钟没有立即适应时间的改变而引起的。
《柯林斯英汉双解大词典》
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It is possible—if statistically extremely unlikely—that Steel could be born a "short sleeper" with an unusual bodyclock, says sleep expert Dr. Sophie Bostock.