46.【答案】C。解析：细节题。根据第一段The key to your problem is that ... at bedtime.可知，你问题的关键就是晚饭后小憩的时间较长。如果你在晚上早些时候不睡觉，那么晚上就能早点睡，故答案为C。

47.【答案】B。解析：细节题。根据第二段Or get together with friends ...time or a little earlier, and you should be able to get a good night’s rest without taking a pill. 可知吃完饭后需要跟朋友聊天，但是不要太晚睡觉，可知C项正确，而B项错误，故答案为B。根据文中Right after your evening meal, engage in some sort of physical activity — a sport such as bowling. 可知D项正确；根据Then go to bed at your usual, time or a little earlier... 可知A项正确。

48.【答案】C。解析：细节题。根据第一段The pill is still working in your system when you get up in the morning. This helps account for the fact that you feel tired all day. 可知安眠药可能会让你白天都不精神，故答案为C。

49.【答案】D。解析：细节题。根据首尾段并联系全文可知D项正确。A项“为了睡得好，你一定不能吃安眠药”说法太绝对；B项“如果你想睡得好就要熬夜”与文章内容(...go to bed at your usual time or a little earlier, and you should be able to get a good night’s rest...) 相悖；C项“如果你晚上失眠，吃东西是有必要的”在文中没有提到。

50.【答案】A。解析：推断题。根据文章的整体语气及话题可知，作者最有可能是个医生，故答案为A。