Maran the Shulchan Aruch cited in the name of the Kol Bo and the Hagahot Mordechai that some are accustomed to sleep on Tisha B’Av tilted on the floor with a stone placed beneath the head. There is an extensive discussion on this matter in the wonderful book Shevet HaKehati (Vol. 2, Siman 191) by Rabbi Gross, Shlit”a, who writes that whoever has the strength should practice this during the day as well until midday. The underlying concept is to change one’s regular sleeping habits, as brought in the Mo’ed LeChol Chai (Vol. 5, Siman 347) in the name of the Vilna Gaon (Gra) that this matter is actually a binding law just like for a formal mourner (Avel). However, I believe that these words apply only to one who is physically strong and whose condition will not be weakened by it, and certainly a sick individual should not sleep on the ground, for regarding illness they were certainly lenient even in actual formal mourning. Therefore, the proper path for one who is able is to follow the conduct of Maran the Steipler, zt”l, which is to lower the mattress onto the floor and place a stone underneath the mattress opposite the head.