Dear Jonathan,

It may come as a surprise that the term Gezel Sheinah does not appear anywhere in the Talmud, Rambam, or Shulchan Aruch, or, for that matter, any of the classic Sefarim in Halachah - Rishonim and Achronim. In fact, the only reference I could find to it was in the contemporary Sefer - Yalkut Yosef - by the present Rishon l'Tzion, Rav Yitzchak Yosef (OC 90:9, #35). In discussing the question of whether to daven with a Minyan on an airline flight, he says that certainly if the Minyan will disturb other passengers and cause Gezel Sheinah then it is best to daven b'Yechidus.

It seems that Gezel Sheinah is indeed forbidden, like anything else that disturbs one's neighbor. The Mishnah in Bava Basra (20b) says that the neighbors are allowed to protest the noise made by one of their neighbors, even though the noise is part of his business, and claim they can't sleep (if he is making the noise inside his house things get a little complicated. See Shulchan Aruch, CM 156:2). So you see that if someone is blasting music and keeping his neighbors up there is grounds for going to Beis Din.

It is also safe to say that in many situations it is permissible to wake someone (an expectant mother needs to wake her husband to tell him she needs to go to the hospital, etc.). So it is a common sense judgement call whether one should wake someone, depending on how compelling the reason is and who is being woken (is he old and sick and really needs the sleep). Here, the Gemara tells us that it is dangerous to drink at night and a person is thirsty, so it seems justified to wake his friend so that he can drink.

Kol Tuv,

Yonasan Sigler

This is not a Psak Halachah