засыпать vs заснуть
zasypat vs zasnut — fall asleep habitually/in progress vs fall asleep once
Register: neutral
What it really means
Засыпать is imperfective for falling asleep as a process or usual pattern. Заснуть is perfective for the one moment of falling asleep. Both are intransitive. Note that засыпать can also mean cover/fill something, but the sleep meaning is clear with a person as subject.
Examples in natural speech
Я обычно засыпаю быстро.
I usually fall asleep quickly.
Ребёнок засыпает в машине.
The child is falling asleep in the car.
Я не мог заснуть.
I could not fall asleep.
Она заснула на диване.
She fell asleep on the sofa.
Постарайся заснуть пораньше.
Try to fall asleep earlier.
Common mistakes
Do not confuse заснуть (fall asleep) with спать (sleep). “Я заснул” describes the transition; “я спал” describes being asleep.
Memory tip
Заснуть is the moment sleep begins; спать is the sleep itself.
Frequently asked questions
What is the difference between засыпать and заснуть?
Засыпать is the process or habit of falling asleep; заснуть is one completed transition into sleep.
How do you say I cannot fall asleep?
Say “Я не могу заснуть” or, in the past, “Я не мог заснуть.”
Is заснуть the same as спать?
No. Заснуть means fall asleep; спать means sleep.
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