A friend of Natalee's was interviewed on O'Reilly. She was in the trip and in the night club. She said that after getting back to the Holiday Inn, she went with friends to some nearby swimming pool...don't know if at the Holiday or elsewhere, and she stayed there until 5 a.m., whereupon she got ready to leave because her plane left at 8 a.m. So she was "out all night" except she was not away from her friends and appeared to be in a relatively safe location. Which was the difference between her being safe and Natalee being missing.
Yes, being up all night is not a bad thing in and of itself. Teens do that, so do college students.
Now if I am up all night it means any number of things, none of them good.