What is the actual issur of gezel sheina and is there a specific story of a gadol who was makpid on this? thank you
Waking somebody up or preventing him from sleep is not included in the formal prohibition of gezel.
Although it is known generally as gezel sheina — “stealing” sleep — the prohibition is more a question of “love you fellow as yourself” than a question of theft.
It can also be considered a form of “damage.”
Please see sources for more details.
The sefer “Ve-Ahavta Le-Re’acha Kamocha” notes that Rav Chaim of Brisk used the expression “gezel sheina,” implying that waking somebody up needlessly is a form of theft.
However, there does not appear to be any grounds for connecting waking somebody up with monetary theft.
It is true that there are other forms of theft that do not involve monetary loss, such as geneivas daas, which the Tosesfta writes is the most severe of all types of theft. However, even the deception of geneivas daas involves taking something from the victim — his daas — whereas preventing somebody from sleeping is a physical nuisance, but doesn’t transfer anything from the victim to the would-be-thief.
This point has been raised by Rav Shmuel Wosner (Shevet Ha-Levi 7:224), who writes that denying the benefit of sleep from a person is certainly a sinful act (see Bava Basra 20b; Shulchan Aruch, Choshen Mishpat 156, concerning the laws of neighbors), but does not fall under the category of theft.
Yet, he notes that it can be considered a form of theft based on the Gemara in Berachos (6b) which notes that somebody who does not answer Shalom to his friend is considered a gazlan. There is, however, room to distinguish between the cases: In the case of answering Shalom, I “owe” my friend the reply and denying it can be considered theft; in the case of sleep, I don’t owe the victim anything.
Rav Menashe Klein suggests that the principle definition of theft is causing the victim suffering, and therefore waking him up can be included in the definition. This is clearly strained, because under so broad a definition any act of harm can be included, so that all physical and emotional damage will be considered theft. This is of course inaccurate.
The Meiri in Bava Basra (20b) actually uses the expression “hezek sheina” in reference to noise that prevent neighbors from sleeping, and it appears that this wording — “sleep damage” — is more accurate that the widely prevalent “gezel sheina.”