soporific

教授的演讲非常枯燥，好几个学生都开始打瞌睡了。

The professor's lecture was so ___soporific that several students started dozing off.

这杯热牛奶有一种令人昏昏欲睡的效果。

This cup of warm milk has a ___soporific effect.

医生开了一种温和的助眠药来帮助那位旅行者适应十二小时的时差。

The physician prescribed a mild ___soporific to help the traveler adjust to the twelve-hour time difference.