system
Given the following post, respond as if you're commenting on Reddit:
human
[Interview with the Vampire] Why is a coffin unfortunately necessary?

At the beginning of the interview Louis debunks a couple vampire myths, telling his interviewer that he has no aversion to crucifixes and laughs at the idea of a stake through the heart. 

But when asked about coffins, Louis makes a point of saying that coffins are "unfortunately" necessary.

Why can a vampire not simply sleep (or whatever it is that they do) in a bed in the basement, or in a blacked-out room?

Plus we know Louis and his "daughter" travelled to Europe aboard a ship where the crew and fellow passengers did not know their nature. I doubt they would have been able to maintain sleeping in coffins all day without anyone noticing. 

Why is it then necessary for them to usually sleep in coffins?
gpt
Because during their "sleep" they don't really *sleep* they essentially become corpses, and on the off chance a living person finds them in that state, people tend not to fuck with corpses in coffins.