Q. Hello Rav,
Due to multiple physical issues I’ve been having, my chiropractor has prescribed that I should sleep on my back with various foam-rolls under my neck and back for as much of the night as possible. The Kitzur Shluchan Aruch says lying on the front or back is not permitted. Is it allowed for medical reasons or is it very strict prohibition? Not sure if this is a factor, but I am married and I’ve never had a problem with nocturnal emissions.
thanks so much.

A. Mishna Berura (239: 6) rules that it is a severe prohibition to lie flat on ones back or front (parkedan). Shalmas Chaim (226) permits awakening someone sleeping in that position.
Although from the Talmud (Brochos 13b), Rashi, Rishonim and Poskim it would appear that the prohibition applies only when someone is sleeping, some Poskim maintain that one should always avoid lying flat on ones back (Divrei Yisroel 3: 137, Piskei Teshuvos 239: 8, et. al.). However, even the above permit, when there are medical issues involved (ibid.).
Medical doctors we consulted were unaware of a natural biological sex arousal reaction in our days when lying in that position.
Horav Shlomo Miller’s Shlit’a opinion is to be lenient in medical need.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a