If you are not tired or you have difficulty falling asleep, you might want to try counting sheep. 但如果你不累或者难以入睡，你可能就会试着数羊了。
One, two, three, four, and by the time you reach five million you should be asleep! 1、2、3、4等你数到五百万的时候你应该就睡着了!
"I nod off right away." “我立刻就打起了盹。”
To nod, "nod," off (two words) means the same as to fall asleep. “To nod off”就是“入睡”的意思。
It's just another way of saying fall asleep, "I nod off." “I nod off”是“入睡”的另一种说法。
Sometimes people will use that expression when they're at a meeting and it is very boring at work, and you may say to someone, "I almost nodded off" — I almost fell asleep. 人们在开会的时候有时会使用这个表达，工作非常无聊的时候，你可能会对某人说，“I almost nodded off”——我差点睡着了。
That usually happens to my students when I am teaching. 我教书的时候，我学生经常会这样。
"Before long," meaning in a very short time, "before long, I'm fast asleep." “Before long”意思是“在很短的时间内”，“没过多久我就熟睡了。”
To be fast, "fast," asleep means to be completely asleep. “To be fast asleep”就是“完全睡着了”的意思。
There's a similar expression that means the same, to be sound asleep, "sound." 还有一个意思相同的相似表达，“to be sound asleep”。
To be sound asleep means that you are sleeping completely, it will not be easy to wake you up. “To be sound asleep”的意思是你完全睡着了，要把你叫醒就很难了。
