2. Pinpoint your sleep style. Then, take stock of your own situation, determining what kind of sleeper you are. Stomach sleepers, for example, need more support than back or side sleepers so their lower back doesn't arch, which can cause pain, says Tishman. And side sleepers should avoid extra-firm mattresses, says Haex, since their bodies will unconsciously start rotating into a prone position in order to get sufficient support.