The "ha" in front of "lailah" is the ordinary definite article,
even though the expression itself has a special meaning.
Like any other definite-article "ha," it should not be filed under. If it is the first thing in a 245, the indicators should be set to 13, and if it would be the first thing in a uniform title, it should be omitted.
The interrogative "ha", on the other hand, is retained and filed
under and capitalized if it comes first in a title.