Q. Can one lie in his back if he will not fall asleep. I find it extremely comfortable and relaxing to lie on my back after the filling Shabbos seuda. Is it a Kiyum (compliance) of Oneg Shabbos (the mitzva of having pleasure during Shabbos) ?

A. On question 1665 we were asked: “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.”

To what we answered: “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”

On question 2725 regarding resting on a hammock laying parkedon or on his back, we wrote: “In regard to resting on a hammock. the Rov’s opinion is that since one lays in an oblong or semi-oval position as opposed to flat, one can be lenient.”

Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a