In it, he writes:
so after like 10 min my friend is telling me that natalee fell asleep i said you kidding just wake her up
My guess is that everything before this sentence is the truth, and everything after it is a lie. They couldn't wake her up. It seems way off that the girl would just "fall asleep" while making out in the back seat.
Could she be hospitalized somewhere or under medical care if she'd had a reaction to a drug? But looks like someone would have come forward if that were the case.