Question about -네(요)
I know that this ending indicates a surprise. When you say it, it means that you impressed or surprised by smth. But there's one thing I can't understand according to this rule. Several times I heard that a person said smth like this:

나 졸리네

What does 네 indicate in this situation? I'm in a doubt about it. I don't think it means like "Oh my, (I've just realized) I'm sleppy."

Question

Question about -네(요)
I know that this ending indicates a surprise. When you say it, it means that you impressed or surprised by smth. But there's one thing I can't understand according to this rule. Several times I heard that a person said smth like this:

나 졸리네

What does 네 indicate in this situation? I'm in a doubt about it. I don't think it means like "Oh my, (I've just realized) I'm sleppy."

Answer

Your understanding about -네 is not wrong but it can be used without any particular meaning in it.
-네 is used to speak casually to speak to oneself.
Even if it is used to mean a surprise, not a strong but a casual and the subtle nuance is noticeable only by native speakers. You are advised to use -네 whenever you want to speak to yourself. (instead of -다)

1) 오늘 참 춥네. (=춥다)
2) 좀 춥네. (춥다)
3) 노래 정말 잘하네! (잘한다)
4) 집이 참 넓네. (넓다)