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 September 4, 2021Have you ever bought a memory foam mattress, then after a year or so of using it, notice a visible sag? You check the warranty, but the sag is not deep enough to justify a repair or replacement from the manufacturer.Don’t ignore the problem! A sagging memory foam mattress won’t give your body the support you need for comfortable sleep, and too many sleepless nights can take a toll on our health. Plus, a lumpy mattress can cause more pressure in some regions of your body and leave sleepers with back pain.Instead of replacing your memory foam mattress, there are three things you can try to minimize sagging and prolong your bed’s lifespan: check the foundation, rotate the mattress, or add a mattress topper or pad.Check the Mattress Foundation and Bed FrameIf you have a saggy memory foam mattress, the problem could be your mattress foundation or bed frame. Both mattress foundations and bed frames are built to raise the bed off the floor and support you and your mattress. Memory foam needs more support because it’s a heavier mattress material. Without sufficient support, you’ll start to see saggy areas.To resist wear and tear, a mattress foundation or bed frame for a memory foam mattress should have a solid or slatted surface. Slats should be no more than 3 inches apart. Wider gaps cause the mattress to dip in between, creating an uneven surface and damaging the bed.The mattress warranty gives guidelines on how the bed needs to be supported. Otherwise, damages from the wrong support voids the warranty. If you already have a mattress foundation and don’t want to invest in another mattress support, you can save money by placing a ¾-inch piece of moisture-resistant plywood below the mattress can boost support.Rotate or Flip the MattressIf you’re noticing body impressions from where you sleep, merely rotating the memory foam mattress can solve the sagging issue. Mattress manufacturers recommend rotating your mattress every three months. This practice evens out wear and tear, and may even extend the life of your mattress.Most modern memory foam beds have a single construction, meaning the mattress isn’t supposed to be flipped. The comfort layers are meant to be at the top and support layers are meant to be at the base of the bed. Flipping the mattress so that the comfort layer is at the bottom can damage the bed and worsen sagging.Dual-sided mattresses are the only memory foam beds that can and should be flipped. Dual-sided beds, as their names suggest, have two different sides you can sleep on. Each side is a different firmness level. Other memory foam mattresses should never be flipped unless stated by the manufacturer.Add a Mattress Topper or PadAdding a mattress topper is the last option to fixing a sagging memory foam mattress. It’s not ideal as a long-term solution because the topper will begin to sag in the same place as the bed. Mattress toppers normally add softness or firmness to an uncomfortable bed. But they can also give you more support and act as a temporary fix to a saggy mattress.Mattress toppers are made of memory foam, latex, and poly-foam. These materials conform to your body’s natural curves and relieve pressure points. When your bed is sagging, a latex topper, in particular, may be the most helpful. Latex is firmer than memory foam and will give you more support.Poly-foam toppers, on the other hand, are cheaper and less supportive. They’re also not the greatest options because they have a shorter lifespan—less than a year compared to the 3 to 5-year lifespan of a latex topper.Mattress toppers are available online and in-store. Some mattress companies make their own toppers to pair nicely with mattress models. You can expect to pay $20 to $250 for a mattress topper, depending on the material and size.Mattress pads are thinner than mattress toppers and may not be as effective in changing the feel of a bed. Many people use mattress pads as a mattress protector—reducing wear and tear on the mattress. Mattress pads provide more cushion than support, and typically contain down, cotton, or polyester fibers.Why Does a Memory Foam Mattress Sag?The main reasons why a memory foam mattress sags include extra body weight, the wrong foundation, and poor support. However, if you’re still experiencing sagging, it may be time to replace your mattress.Body WeightEvery night your memory foam mattress bears your body weight and adapts to your movements. Over time, the constant pressure starts to break down the foam layers, causing a visible sag. A bed is less likely to sag if it’s 10 to 12 inches thick.A thinner mattress has thinner layers which break down faster than thicker layers. Hence, why pillow tops wear down within 2 years, while memory foam comfort layers last longer (because they’re thicker).Before buying a mattress, consider the combined weight of you and your sleep partner. Most mattress models have a weight limit listed. Before purchasing a mattress foundation or bed frame, read the fine print to ensure you’re not over the weight limit. If you don’t, your memory foam mattress may end up sagging faster, and you may have to look into replacing the bed sooner than you expected.Wrong FoundationPairing your memory foam mattress with the right foundation, like a platform bed frame, may prevent premature sagging. The wrong foundation, especially one with slats wider than 3 inches, won’t offer adequate support for your mattress and cause sags and indentations.For example, box springs are better paired with innerspring mattresses. Memory foam is too heavy for a box spring, plus the innerspring coils can poke through and damage the foam layers. If you have a box spring, add a ¾-inch-thick piece of moisture-resistant plywood between the mattress and the box spring to improve support and protect your bed.Poor SupportHigh-quality mattresses usually contain more than a comfort and support layer. Mattress manufacturers add a transition layer between the comfort and support layers to provide extra cushion and lend more support. The support layer should be thicker than the comfort and transition layers.The bottom layer is the support layer and is responsible for distributing body weight and overall durability. Without long-lasting support, your bed will end up sagging within a couple of years. If you start to notice deep depressions, try adding a mattress topper to give your bed more support or rotate the bed to even out wear.Read the WarrantyBefore buying a mattress, take a look at the warranty. Most beds come with a standard 10-year warranty that protects the customer from replacing the mattress if it develops visible sags or indentations. Instead, that responsibility falls on the mattress company.Mattress warranties also cover manufacturing defects in addition to sagging. Most mattress companies will repair or replace the mattress if it sags more than 1 inch, but this measurement depends on the brand.If sagging is too shallow for a warranty claim, you can use any of the above tips to restore your bed to its original shape.FAQsWhen should I replace my memory foam mattress?A memory foam mattress can last up to nine years, but you should look into replacing it after seven. Constant use wears out the mattress and gradually loses support over time. Also, if the mattress surface is lumpy or uneven, or if you notice a visible sag, it might be time to replace your mattress.Will a memory foam mattress topper help a sagging mattress?Memory foam mattress toppers are a temporary solution to a sagging mattress. We don’t recommend adding a mattress topper to a sagging mattress because the topper will soon sag in the same areas as your mattress. If you’re looking for a mattress topper, one with a firmer feel will give you more support if your bed starts to sag.Should you flip a memory foam mattress?Unless it’s dual-sided, you should never flip a memory foam mattress. Memory foam beds are designed as a single structure. Comfort layers are meant to rest on top of the mattress, while the support layer is the foundation. Flipping a memory foam mattress when you’re not supposed to will damage the comfort layers and may cause the bed to sag.How many years does a memory foam mattress last?A high-quality memory foam mattress lasts 7 to 9 years. The bed’s lifespan also depends on how well it’s maintained. Rotating the mattress every three months evens out wear and tear. You should also vacuum the mattress every six months to remove dirt and allergens and keep the bed fresh and clean.Do memory foam mattresses get softer with use?You may have noticed the memory foam mattress you tried out in a showroom is softer than the new one you bought—this is normal. Memory foam naturally softens under heat and pressure, but it’ll also soften as you break into your mattress. It takes about 30 days to adjust to a new sleep surface.ConclusionYou may experience more aches and pains with a sagging mattress. Instead of getting rid of a memory foam mattress in excellent condition, use one of our helpful tips to bring back the bed’s solid surface. Simply installing mattress supports, rotating the bed, or adding a mattress topper can prevent deeper sagging. It can also give you the support you need for a good night’s sleep.About the author Malik Karman“Professional sleeper” Malik Karman is a freelance writer for the eachnight blog. Over the years, Malik has read countless medical studies and explored hundreds of different bedding products in an effort to better understand what goes into a restorative night’s rest. Malik curates many of our “best mattress” guides to assist readers in the mattress buying process. Find more articles by Malik 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.