This is the 16150th most frequent Korean word.
불면증
Insomnia.
Here, '불면증' is used as the subject causing the effect (lack of sleep).
나는 불면증 때문에 매일 잠이 부족하다.
I lack sleep every day because of insomnia.
Here, '불면증' is the object of the action (overcoming).
불면증을 극복하려고 노력하고 있어요.
I am trying to overcome insomnia.
Here, '불면증' serves as a general topic or subject being discussed.