People with back pain often think that a very firm mattress is best. Not true. In a study published in The Lancet, 313 individuals with low-back pain slept on either a firm or a medium-firm coil mattress. After 90 days, the participants with the medium-firm mattresses had less pain in bed, upon rising and during the day than those with firm mattresses. Other misconceptions about beds and back pain…

Misconception: Everyone with back pain feels the pain when he/she first wakes up — so you can’t tell if the mattress is a problem or not.

Fact: Most back pain is mildest in the morning, before you get out of bed and begin moving. If you wake up stiff and sore, your mattress may be to blame. Try sleeping on a different mattress — in the guest room, at a friend’s, in a hotel — and see if you notice an improvement when you get up.

Misconception: Heavier people with back pain need soft beds.

Fact: Everyone needs enough support during the night to keep the spine in a normal position. If the spine sinks into a sagging bed, the muscles are strained. Heavier people and those who sleep on their backs tend to need firmer mattresses. Side and stomach sleepers need softer beds.

Misconception: A foam pad or an entire mattress made of foam helps relieve back pain.

Fact: There are two kinds of foam generally available — egg-crate and memory foam. Egg-crate foam creates a layer of softness but does not change the support beneath. Memory foam is sensitive to temperature and conforms to the body. However, there is no scientific evidence that either kind of foam reduces back pain.

Misconception: Adjustable beds can ease back pain.

Fact: Some adjustable beds are filled with air or water that can be pumped in or out. Other types have joints that allow parts of the bed to be propped at different angles. There are no authoritative studies showing that adjustable beds help reduce back pain.

Misconception: You can’t tell in the store if the mattress is right for you.

Fact: Trying out a mattress in the store can help you determine if it’s comfortable. Lie on each mattress for at least five minutes. Start on your back, without a pillow. Your hand should fit snugly in the small of your back. Lying on your side, you shouldn’t notice significant pressure on your hips or shoulders. Choose a retailer that will allow you to return a mattress if it isn’t comfortable. These include Sleepy’s and 1800Mattress.com. (You may have to pay an exchange fee.)