Halakhah zu Tehillim 4:5

The Sages teach (Berakhot 60b), “When going to bed one recites Shema until Ve-haya im Shamo’a (i.e., the first paragraph of Shema) and says the blessing ‘Barukh Ha-mapil Ḥevlei Sheina…’ (‘Who brings the bonds of slumber down upon my eyes…’)” Likewise, R. Yehoshua b. Levi said, “Even if one recited Shema in the synagogue, it is a mitzva to recite it on his bed.” The Sages support their words with the verse (Tehilim 4:5), “Meditate in your hearts [while] on your beds, and be silent sela” (Berakhot 4b). There is no difference between men and women concerning these laws.¹Although MA (239:2) states that women do not customarily recite Ha-mapil because it is a time-bound commandment, still, the remaining poskim (SHT 239:16; Kaf Ha-ḥayim 239:3; Halikhot Shlomo 13:22) maintain that since the recitation of Shema and the Ha-mapil serve as protection, and women need protection just as much as men, women, too, must recite Shema and say Ha-mapil.

One who is sick [may] pray even lying down on one's side, as long as he is able to concentrate (And if it is not possible from him to pray, nevertheless, one should meditate in one's heart, as it says "Ponder [it] on your bed" [(Psalms 4:5)] (Beit Yosef in the name of Orchot Chaim and Pesikta).