Jet lag is back on the agenda for business travelers, especially as long-haul international traffic picks up again.

There is endless advice online about jet lag. Drugs are frequently mentioned, and a recent favorite is Nuvigil, used to treat excessive sleepiness. Nuvigil’s manufacturer, Cephablon, has so far not succeeded in obtaining government approval for its plan to market the drug as a remedy forjet lag.

But the approach I hear most often from long-haul travelers involves diet and preparation. " Why would you take a pill that your body then has to shake off " said Lynne Waller Scanlon, the author, with Charles F. Ehret, of Overcoming Jet Lag, which was a best seller in the mid-1980s but went out of print until she revised and republished it last year under a snappier title, The Cure for Jet Lag.

The book lays out a treatment system for jet lag based on pre-trip diet and conditioning to reset the body’s internal clock. The book suggests resetting the body clock so that it will be in sync with the time at the destination. One to three days before a trip, the authors suggest low-calorie meals. In flight, avoid or strictly limit alcohol, and use coffee or tea to persuade the body clock that it’s daytime. If it’s morning after flying all night, resist sleep and " flood your eyes with daylight " , they suggest.

While all long-haul travel can cause normal fatigue, travel across time zones causes the body to react with the most pronounced effects of jet lag, including disorientation and a general sense of discomfort.

In the last few years, the global airlines have put more emphasis on accommodating the need for in-flight sleep—at least in the business and first—class cabins, where international airlines earn most of their revenue. But at the same time, international airlines also promote extensive in-flight entertainment selections, as well as high-end menus, including quality wine lists, in premium classes. Indulging in these would seem to work against dietary treatment to combat jet lag. But Ms. Scanlon says recovery is nevertheless attainable.

" What do you do if you can’t implement this program ahead of the trip, or if you’ve blown it and had a complete debauch on the plane " she said, " Well, when you get off that plane, you get on the program right away. It may not be perfect, but you will feel much, much better.

According to Paragraph 5 and 6, which of the following statements is TRUE（）

A. Effects of jet lag after travels across time zones are most serious and obvious

B. Effects of jet lag are a sense of discomfort and the loss oforientation

C. Things have improved in recent years because the global airlines have emphasized on meeting the need for in-flight sleep

D. Enjoying the in-flight entertainment and high-quality food will make it impossible to recover from jet lag