An extra firm mattress isn’t the best bed for everyone. Many sleepers, such as side and petite sleepers, will likely wake up with aches and pains if they sleep on a too-firm mattress. However, some sleepers will benefit from a firm mattress, such as stomach sleepers. There’s no such thing as a “good” firmness or a “bad” firmness. Everyone has different sleep needs, which means everyone has a mattress firmness that’s best for them.