There are several verbal expressions in English using the noun sleep which refer to the moment when you start to sleep. When you go to bed at night, you normally go to sleep or fall asleep. When you go to sleep, it is usually a deliberate action. He didn't want to go to sleep. You can fall asleep by accident, or at a time when you should be awake. I've seen doctors fall asleep in the operating theatre. If you have difficulty sleeping, you can say that you cannot get to sleep. Sometimes the fever prevents the child from getting to sleep.
英语中有几个用 sleep 的名词形式表示开始睡觉的动词短语。晚上上床睡觉的时候通常用 go to sleep (上床睡觉)或者 fall asleep (睡着)。go to sleep 通常指一种清醒时有意为之的行为，如：He didn't want to go to sleep (他不想上床睡觉)。fall asleep 可以指无意中睡着，或是在应该清醒的时候睡着，例如：I've seen doctors fall asleep in the operating theatre (我见过医生在手术室里睡着的情形)。假如无法入睡，可以说 cannot get to sleep，如：Sometimes the fever prevents the child from getting to sleep (有时候发烧使孩子无法入睡)。