高中(學測,指考)◆英文題庫下載題庫

49-52為題組

        Jet lag, caused by traveling between time zones, is becoming a common problem for frequent travelers: for 49 per cent it is only a nuisance and for 45 percent it is a real problem. It is caused by disruption to the internal biological clock, and may lead to digestive problems, tiredness, and sleep disruption.

        Generally speaking, our biological clock is slightly disturbed if we just move into the next time zone, but jet lag becomes a problem once we have passed through three or four time zones. The body takes about one day to get over each hour of time difference. But the seriousness of jet lag problems also depends on our direction of travel. If we go north or south, we won’t notice any difference, because there is usually no time zone change. However, if we travel west we will be in advance of ourselves as far as our internal clock is concerned, and problems may arise. A west-to-east journey, on the other hand, makes us late compared to the local time. It often demands even greater effort in adjustment since we are not quick enough to catch up with the new time schedule. Therefore, a trip from New York to Los Angeles often causes fewer problems than a Los Angeles-New York trip.