What is haunting Lana while she's asleep?

Something seems to be troubling Lana while she's asleep. And it's all a bit freaky to understand...

Lana struggled to sleep last night, but in those moments she did fall asleep, she awakens in some sort of unexplained, bizarre scenario that she has no recollection of.

From wet grassy feet to emails that are written for her - what is going on when Lana's asleep?