That is a great question Saeed! I am not an English teacher, but I found a couple of references on the internet to using "present tense in the past".
Of course in past tense, one would write "Yeah, she woke up last night and muttered "vampire" and then passed out."
But instead, the writer, who is describing his personal experience, is writing in a style that puts you (the reader) with him in the story last night.
I would say it is a style of writing that livens up the story.
Here is another example: "Yesterday I am driving this motorcycle so fast and a dog runs in front!".
Doesn't it make you feel like you are more involved in the writers story? - you are there!
This "style" is very common in conversations in the US among young people who are relating their recent parties and escapades!