1,348. Sitting on a Chair

210:9 A mourner is permitted to recite the bracha of shehechiyanu, even during shiva, if a situation calls for it, such as on Chanukah, over a new fruit, etc.

211:1 The entire week of shiva, the mourner is not permitted to sit on a bench, nor on cushions or pillows; he may only sit on the ground. However, a sick or older person who would be in discomfort from sitting on the ground may put a small cushion under himself. The mourner is permitted to walk and to stand, and he need not sit except when visitors come to console him.

Similarly, the mourner is not permitted to sleep on a bed or a bench, just on the ground. He may, however, place cushions or pillows under himself as he does when lying in bed. Some authorities permit sleeping in a bed and some people follow this practice because their weak constitutions make them like sick people in this matter.