Eachnight may earn commissions for products you purchase through our links. Our articles and reviews include affiliate links and advertisements, including amerisleep advertising. Learn more Updated August 17, 2021If you’re waking up sore or unrested every morning, it may have nothing to do with your sleep position or daily activities—you could just have the wrong mattress. When shopping for the best mattress, you can’t just go down to the furniture store and pick the first one that feels nice. Comfort is important, but there are other factors that just as strongly influence what kind of mattress you need. Your ideal firmness level is dictated not only by your personal preferences but also by your body type and sleep style.Firm and Soft—What’s the Difference?Mattress firmness is measured on a scale of 1 to 10, with 1 being the softest. However, it’s very rare to find mattresses softer than a 3 or firmer than an 8—a lot of manufacturers don’t make extra-soft or extra-firm mattresses because they’re too extreme for most consumers. (However, with a little bit of digging, you can find comfortable extra-firm and extra-soft mattresses sold by certain brands.)Soft mattresses will generally land somewhere around 3 on the firmness scale, while firm mattresses come in around an 8. Manufacturers rate their own mattresses, so there might be a little bit of variance from one mattress company to the next, but most of the time this variance will be small enough you still know what you’re getting.Firm MattressesFirm mattresses are better for back sleepers, stomach sleepers, and heavier sleepers (230 pounds and up) because they don’t compress as much as soft mattresses, keeping stomach and back sleepers’ spines aligned and body weight evenly distributed. They’re also good for hot sleepers because they’re not overly cradling, so body heat can escape out of firm mattresses more easily.ProsPromotes spinal alignment for back and stomach sleepersMay help with back pain for some sleepersCan usually accommodate heavier sleepersSleeps coolerConsCan cause pain and pressure points for side sleepers and people with more petite framesNot overly comfyMay not offer enough cushion for people with joint painSoft MattressesSoft mattresses are normally a better option for side sleepers and lighter weight sleepers, as their soft surfaces relieve pressure points around the shoulders and hips and compress enough to cushion even the lightest of sleepers.ProsReduces pressure pointsComfortable for people with certain conditions like arthritis, scoliosis, sciatica, etc.Better for lighter weight sleepersConsMay not support spinal alignment for back and stomach sleepersMay cause sinkage for heavier sleepersMay sleep warmer than firm mattresses since they offer more cradlingFinding the Best Firmness Level for YouYour preferred sleep position is the number one thing you need to think about when deciding on mattress firmness. How you sleep at night dictates where you’re most likely to experience pressure points, which part of your body is going to compress the bed the most, and how the bed is going to distribute your weight.Back SleepersSleeping on your back means your hips and buttocks tend to sink into the bed, so a firm mattress is a good option to keep the heavier parts of your body lifted, your weight evenly distributed, and your spine aligned. You want your mattress to be firm enough that it supports your pelvic area, but not so firm you can put a hand between your lumbar region and the mattress like you’re lying on the floor.Side SleepersSide sleepers’ pressure points need extra cradling, meaning a softer mattress will probably be better for them. While in the side sleeping position, you want your shoulder and hips to compress the mattress enough so the joints are cushioned but your torso and legs are still supported—keeping your spine straight and your hips aligned. Side sleepers can get comfy sleep on a soft mattress, but some side sleepers like medium mattresses, too.Interested in learning more about the best mattresses for side sleepers? Check out our other review guide.Stomach SleepersYour spine tends to arch too much when you sleep on your stomach because your torso and pelvis sink into the bed, and over time, this can lead to chronic low back pain. Stomach sleepers need a firm mattress to counteract this effect, as a firm mattress can keep the hips lifted and spine in a neutral position while sleeping on your belly.Combination SleepersIf you like to change positions a lot during the night, we recommend a medium mattress. Medium mattresses can offer you both enough compression to cushion your shoulder and hip joints when you’re on your side as well as enough firmness to lift your pelvis when you’re on your back or stomach. Mediums also won’t compress so much they make moving around during sleep more difficult.FAQsDoes mattress material affect firmness?A mattress’s material affects a lot of things, from feel to heat retention to durability to motion transfer, but it has little impact on how hard or soft your mattress is. All mattress types are available in all firmness levels, meaning you’ll be able to choose between firmness levels whether you buy memory foam, latex, hybrid, or innerspring.Is my mattress too firm or too soft?Waking up with pain in some part of your body is generally the first clue something’s off with your mattress firmness. Side sleepers may experience pain and stiffness around pressure points or frequently wake up to find their bottom arm has fallen asleep, and both of these issues are signs you may need a softer mattress. Conversely, if you’re a stomach or back sleeper and waking up with lower back pain every morning, your mattress may need to be firmer.How much softer will my mattress get over time?Most mattresses soften up eventually, but how much they soften depends on the type of mattress. Innerspring mattresses won’t lose a noticeable amount of firmness after you purchase them. But foam mattresses can react to pressure and body heat, meaning they’ll lose some firmness once you bring them home and sleep on them for a few weeks. That’s why it’s vital to ensure your mattress comes with a (risk-free) trial period of at least 90 days. That way, you can return it (for free) for a refund if it turns out it doesn’t work for you.What if my partner and I need different firmnesses?Split kings are a great option for couples with vastly different firmness needs. A split king allows you to buy a king sized bed frame and put two twin XL mattresses on it. That way, you can both choose the mattress model of your ideal firmness. As an added bonus, the split king allows couples to use split adjustable bed frames and adjust each side of the bed to their desired angle for sleeping.Does firmness make a difference in how long a mattress lasts?Possibly, but not that much. Firmer mattresses might be a tad more resistant to sagging, but the quality of your mattress materials and construction, and how well you take care of it, are going to have a whole lot more to do with how long it lasts than firmness does.If you want to make your mattress last longer:Use a mattress protector to shield it from stains, bed bugs, and other germs.Wash bed linens regularly.Properly support your mattress with a quality mattress foundation or platform.Bottom LineAs you can see, your ideal mattress firmness level can be influenced by a lot of important considerations, from your body weight to your favorite sleep position. Even if you spend a year researching the best mattress for you, you’ll never really know if it’s a perfect fit until you try it out for a month or two. All mattresses come with an adjustment phase of a few weeks to a couple of months, so whatever you do, don’t get a mattress without a sufficient trial period—it’s the best thing to determine the right mattress for your needs.About the author Kiera PritchardKiera Pritchard’s curiosity around dreams and dreaming sparked her passion for sleep science. In addition to freelancing for eachnight, Kiera is also a physical trainer and strives to help others lead healthy lives while asleep and awake. Since joining our team, Kiera has compiled multiple sleep health guides offering our readers advice on how to improve their days and evenings. Find more articles by Kiera Comments Cancel replyLeave a CommentYour email address will not be published. Required fields are marked * Comment Name Email I agree to the Terms and Conditions of this website.