geokjeongi manhaseo jami an wasseoyo.

I was so worried that I couldn’t fall asleep.

Breakdown of geokjeongi manhaseo jami an wasseoyo.

• ~이: subject particle
• 오다: to come
• 많다: many
• 안: not

Questions & Answers about geokjeongi manhaseo jami an wasseoyo.

Why is it 걱정이 많아서, not 걱정을 많아서?

Because 많다 works like to be many / to be a lot, so the thing that is “many” takes a subject marker: 이/가.

• 걱정이 많다 = literally worries are many
• Natural English: to have a lot of worries / to be very worried

So:

• 걱정이 많아서 = because there were many worries / because I had a lot on my mind

Using 걱정을 많아서 would be ungrammatical here.

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What does -아서 mean in 많아서?

Here -아서 / -어서 connects two clauses and gives a reason or cause.

So:

• 걱정이 많아서 = because I was worried a lot / because I had many worries
• 잠이 안 왔어요 = sleep didn’t come

Together:

• 걱정이 많아서 잠이 안 왔어요 = Because I was so worried, I couldn’t sleep

In this sentence, -아서 is basically functioning like because or so.

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Why is it 잠이 안 왔어요? Why is sleep marked with 이?