Answer keys and explanations：

　　1. True

　　See para.3 from the beginning： Zolpidem， sold under the brand names Ambien， Stilnoct and Stilnox， is widely prescribed to treat insomnia and other disorders such as sleep apnea.

　　2. False

　　See para.1 under the subtitle “Midnight snack”： Another case involved a woman who gained 23 kilograms over seven months while taking zolpidem. “It was only when she was discovered in front of an open refrigerator while asleep that the problem was resolved”…

　　3. Not Given

　　See para.2 under the subtitle “Midnight snack”： The UK’s Medicines and Healthcare products Regulatory Agency， meanwhile， has recorded 68 cases of adverse reactions to zolpidem from 2001 to 2005. (The time the drug was approved in the UK was not mentioned.)

　　4. True

　　See para.3 under the subtitle “Midnight snack”： In one case， a transatlantic flight had to be diverted after a passenger caused havoc after taking zolpidem.

　　5. False

　　See para.2 under the subtitle “Tried and tested”： He says that unlike older types of sleep medications， zolpidem does not carry as great a risk of addiction.

　　6. Not Given

　　See para.3 under the subtitle “Tried and tested”： And Wright notes that some of the reports of “sleep-driving” linked to zolpidem can be easily explained： some patients have wrongly taken the drug right before leaving work in hopes that the medicine will kick in by the time they reach home. (No patients as office workers are mentioned in the passage.)

　　7. C

　　See para.4 from the beginning： A newly published report from Australia’s Federal Health Department describes 104 cases of hallucinations and 62 cases of amnesia experienced by people taking zolpidem since marketing of the drug began there in 2000. The health department report also mentioned 16 cases of strange sleepwalking by people taking the medication.

　　8. B

　　See the sentence in para.2 under the subtitle “Hypnotic effects” (The product information for prescribers advises that psychiatric adverse effects， including hallucinations， sleepwalking and nightmares， are more likely in the elderly， and treatment should be stopped if they occur.) and the sentence in para.3 under the subtitle “Tried and tested” (Doctors “not the product information” stress that the medication should be taken just before going to bed.)

　　9. B

　　See para.5 under the subtitle “Tried and tested”： Sanofi-Aventis spokesperson Melissa Feltmann … says that “the safety profile [of zolpidem] is well established”.

　　10. 674，500 (times)

　　See para.3 from the beginning： Various forms of the drug， made by French pharmaceutical giant Sanofi-Aventis， were prescribed 674，500 times in 2005 in the UK.

　　11. (a) benzodiazepine-like (hypnotic)

　　See para.1 under the subtitle “Hypnotic effects”： The drug is a benzodiazepine-like hypnotic (类苯二氮催眠药)that promotes deep sleep by interacting with brain receptors for a chemical called gamma-aminobutyric acid.

　　12. risky consequences

　　See para.3 under the subtitle “Hypnotic effects”： Patient advocacy groups … stress that strange sleepwalking and sleep-driving behaviours can have risky consequences.

　　13. Food & Drug (Administration)

　　See para.4 under the subtitle “Tried and tested”： The US Food & Drug Administration says it is continuing to "actively investigate" and collect information about cases linking zolpidem to unusual side effects.