单选题 Most people who travel long distances complain of jetlag (飞行时差反应). Jetlag makes business travelers less productive and more prone 21 making mistakes. It is actually caused by 22 of your "body clock"—a small cluster of brain cells that controls the timing of biological 23 . The body clock is designed for a 24 rhythm of daylight and darkness, so that it is thrown out of balance when it 25 daylight and darkness at the wrong times in a new time zone.
The 26 of jetlag often persist for days 27 the internal body clock slowly adjusts to the new time zone. Now a new anti-jetlag system is 28 that is based on proven 29 pioneering scientific research.
Dr. Martin Moore-Ede has 30 a practical strategy to adjust the body clock much sooner to the new time zone 31 controlled exposure to bright light. The time zone shift is easy to accomplish and eliminates 32 of the discomfort of jetlag. A successful time zone shift depends on knowing the exact time to either 33 or avoid bright light. Exposure to light at the wrong time can actually make jetlag worse. The proper schedule 34 light exposure depends a great deal on 35 travel plans. Data on a specific flight itinerary (旅行路线) and the individual"s sleep 36 are used to produce a Trip Guide with 37 on exactly when to be exposed to bright light. When the Trip Guide calls 38 bright light, you should spend time outdoors if possible. If it is dark outside, or the weather is bad, 39 you are on an aeroplane, you can use a special light device to provide the necessary light 40 for a range of activities such as reading, watching TV or working.