How to Make a Mattress Firmer With a Bed Board
How to Make a Mattress Firmer With a Bed Board
- 1 Chemicals in Foam Toppers
- 2 Reduce Wood Bed Noise
- 3 Build Wooden Bed Rails
- 4 Ways to Firm Up Your Old Mattress
A comfortable mattress is key to a good night’s sleep, which is key to the quality of your day. A mattress that is too soft for your liking may cause aches and pains or result in a less-than-restful night. Firm up that sagging nightmare by placing a bed board beneath it. Bed boards come in all shapes and sizes, some designed for use between a mattress and box spring, some with just a mattress. You can also make the bed board yourself from plywood, firming up that saggy situation once and for all.
The Plywood Sandwich Solution
Plywood cut to the size of the mattress acts as a do-it-yourself mattress support that fits between mattress and box spring, making a mattress firmer. This comes in handy for a mattress that’s too soft overall, or for a mattress or box spring that sags in some areas due to age. Measure the mattress and cut a sheet of 3/8-inch plywood to the same size; this may require two sheets of plywood if the bed is queen size or larger. To achieve curved corners matching the mattress, set the mattress atop the cut plywood, trace the corners, then saw along the traced lines. Sand the board and edges smooth to prevent snagging or splinters, wipe the dust away and then set it on the box spring with the mattress on top.
Mattress-Only Support System
If your mattress has no box spring as support – for instance, a foam or latex mattress designed for use without the box springs, or on a platform bed designed for just a mattress, plywood comes to the rescue once again. Remove the mattress from the bed frame and measure the inner frame area upon which the mattress rests. Cut the plywood to size, then place it in the frame bottom. Depending on the frame type, you may wish to bolt the plywood down by drilling holes through both the plywood and frame. If the bed has slats to support the mattress, set the plywood atop the slats or remove the slats entirely.
Hinging on Comfort
Some premade bed boards are hinged, designed to use with adjustable beds such as hospital beds or home-based versions with head- and foot-raising capabilities. These are available in hospital supply stores in various sizes compatible with common mattress models. Some versions are thin and fold up, accordion style. Hinged or folding bed boards are designed for use between the mattress and box spring.
Bunky Board Bolster
A bunky board – a foam-covered, thin support typically used for bunk beds and platform beds – works much like plywood to make a mattress feel firmer. These are sold in shops that sell bunk beds and come in standard bunk bed and platform bed sizes, such as twin, full and queen.
How To Make A Mattress Firmer
A comfortable mattress is the ingredient of a good night’s sleep. Each of us has different preferences regarding comfort, and the same goes for mattresses. You should buy a mattress that fits your needs, but sometimes things can go wrong; you may end up with one which is too soft. Mattresses can also get saggy and lose their form over time due to wear and tear.
Replacement is not always an option and of course, it does not apply for new ones. So today we are going to offer you some simple tips on how to make a mattress firmer.
Table of Contents
Make Your Mattress More Firm: 6 Easy Steps
1. Manipulating Bedroom Temperature
Temperature can affect the firmness. Generally, higher temperatures make it soft, while a colder environment makes it firm. So you can try lowering down the bedroom temperature using an air conditioner for a firmer finish. This will ensure that your sleep surface remains at a temperature that you love. Plus, it can significantly affect mattress life and longevity considering hot environments can cause sagging and hence reduce its overall lifespan.
2. Using Toppers
Mattress toppers are mini sheets of memory foam or latex that can be put over the existing mattress surface to add support and make it firmer; these are typically anything between 2-6 inches in height. They also come in other fillings such as polyester, cotton, wool, and other natural and synthetic materials, which are usually much thinner (approx 1-2 inches) and are often calledpadsas opposed totoppers. Pads will most likely make your sleep surface softer, so best to avoid these. Buy a topper matching your current bed size for a cheap but effective solution. They come with straps that can be used to hold them in place. It is easy to attach them and add robust support for extra support.
3. Using Plywood Support
Lack of adequate support can make even the best mattress feel softer than usual. For best results, you can place a piece of plywood underneath when the boxsprings are no longer proving enough support. One thing to note is the plywood should match the mattress dimensions exactly; too small and there will be overhang, too large and the wood may protrude and cause injury. Additionally, smooth out the edges so that sharp corners are removed. You should check your manufacturer for recommendations before placing the plywood as it can sometimes invalidate the warranty. If placing the plywood does not solve your problem, then try replacing the boxspring.
4. Place It On The Floor
If it is not possible to follow the above methods, then you can place the mattress on the floor instead. Of course, there are certain things you need to keep in mind when placing on the floor, such as dust and bugs from the carpet, or colder temperatures emitting from tiled or laminate flooring, or even cold drafts from nearby doors. If done correctly, this can be a cheap way to make any which is soft to become firm. For more information, check our latest post on floor mattresses.
5. Flip It
Some mattresses can be used on both sides, but not all. If yours is a double-sided, then it’s possible. If it isn’t double sided then you may cause more damage than good. By flipping a mattress over onto the other side it can cause the surfaces to wear evenly, thus increasing the lifespan. Try flipping every so often, perhaps every 6 months or so. Regular changing of sides makes it retain shape for a more extended period.
6. Killing Bacteria
Another excellent way to make firmer is to have it out under the sun. You could do it every few months. Not only does it dry out and resolve mold, damp and mildew issues, but it can also kill many germs and bacteria as well. While not as effective as when you give it to a professional cleaner, it is definitely one of the things that you should try out which will make a difference.
The six things mentioned above are the cheapest and easiest methods. Which one you choose depends on your circumstances and budget, but as you can see it is quite simple to achieve effective results in a DIY fashion with little or no cost at all. Try some of them out, almost certainly you will see good results instantly.
6 Easy & Simple Ways to Make Mattress Firmer
A mattress definitely holds the key position when it comes to defining a good night’s sleep. It is important because, without having a proper mattress, you may not even think about having a calm and consistent sleep overnight. You will find yourself turning and tossing and may end up with groggy feelings in the morning.
To make sure you sleep better and enjoy a consistent sleep, you should consider buying a mattress which is thick enough to provide you the desired comfort and also is soft or firm depending on what your body needs.
However, there is a problem here, when you buy a new mattress it’s too soft or after using for a time your mattress become softer,… and your body do not like that. Do not worry! In this article, we’ll show youhow to make mattress firmerin simple and affordable ways.
Why thickness and firmness of your mattress are important?
Regarding the thickness and the firmness of the mattresses, we can say that you should select according to the way you sleep or what are the basic requirements or expectation you have while using your mattress.
Like if you are a side sleeper, you might be in need of a medium soft mattress whereas if you are a back sleeper you may need to get a firmer mattress. For the belly sleepers, it is always a good choice to buy a soft mattress.
But it is also true that when you buy your mattress it may be a little firm, but as the time passes the firmness of the mattress gets vanished or may slightly deteriorate due to the external factors and usage of the mattress.
Why mattresses lose their firmness?
The mattresses may lose their firmness because of the moisture, heavy usage, insufficient care, and lack of proper placement of the mattress. And if you are in need of a slightly firm mattress, you may need to treat it through proper ways so that you can restore its actual firmness or at least support it using different accessories to gain the firmness again.
Your Mattress is Too Soft? How To Make Mattress Firmer?
An easy way out to make sure you have a firmer mattress again is to replace it with a new one. But you should be aware of the fact that replacing your mattress may cost you 500-1000usd or more depending upon the kind of mattress you have or want to replace your old mattress. So, better not to go with the replacement option and try to look into easier, low cost and wise solutions, instead.
#Replace the worn out layers:
If you have a mattress having multiple layers, you may try changing the above layer and see if that works for you. It will cost a lot lesser than changing the whole mattress and you will get a firm support again.
#Give it a firm platform
Try to put your mattress on a plywood bed support. This will ensure that your mattress is supported in a firm way so that no part is sagging and will be kept straight.
#Use a firm mattress topper
Using afirm mattress topperis one of the easiest ways to get the firm mattress surface. You should use alatex mattress topperor ahigh-density memory foam mattress topperfor a firm yet adjustable support. Latex and memory foam toppers are the best choices to make mattress firmer.
If your existing mattress is too soft, you should buy a latex topper, because naturally, latex is firmer than memory foam.
In case you need soft yet form upper layer, you may choose a cotton filled mattress topper. A well-fitted mattress pad and cover can also supplement in retaining and enhancement of mattress firmness.
A mattress topper acts in protecting your mattress in many different ways.
- One is that your mattress will have an extra layer which will be affected when you use your mattress and in the way and the actual mattress does not get direct affect on its surface.
- It gives an extra soft or firm layer on the top of your bed, keeping it firm and in the actual form of the mattress, the way the mattress was before.
- You should use a memory foam mattress topper if you have to get the firmness back for your side sleeping habit. This will give you medium firmness and a very good night’s sleep.
- For those who need to transform into a new mattress through a mattress topper, a latex mattress topper would be the best.
The mattress topper only works on the mattresses which have minor sagging issues and not too damaged. Also, the mattress toppers can only supplement the mattress firmness on the top and they may not fix it if your mattress got damaged
#Keep the room temperature at an optimum level
Highs and lows in the room temperature can also affect the firmness of the mattress. If you could keep it normal, you can easily avoid the deterioration process of the mattress.
#Give your mattress a sun bath
Make sure you put your mattress under the sunlight after every few months. This will help the mattress rejuvenate its internal structure by stretching the cells and killing germs and mildew and release moisture.
#Flip your mattress often
Make sure you flip your mattress on a regular basis. This practice will help you retain the shape of the mattress and the mattress will not be overly used from one side or spot. When all areas get equal pressure, the deterioration process will be slow.
Among all these tips, we may consider two things the most important ones, moisture and wrong placement of the mattress may lead to the loss of firmness. So, if you can protect the mattress from these two factors, you can surely make it feel firmer and supportive.
ANNA PATON says
Thank you that was very helpful. My bed is soft/plush and I wake up with lower back pain which goes after 10 mins. I am 68 years old so could be an ‘age thing’ I will get a firm memory foam topper see if that helps. Also do some back stretches my physio taught me
You’re welcome, Anna.
You can take a look at this article to choose the best topper for your back: Best Mattress Topper for Back Pain
Hi I have a soft memory foam bed as well and wake up with lower back pain too. My older conventional mattress did not give me any pain. I think it’s probably your mattress, it should be firmer to avoid the pain contrary to some articles advice. Good luck.
Claire Bell says
Hi, I have been searching the Internet for approx 2 hours and this is the only site I have managed to find that someone “in the know” actually replies. I would appreciate it greatly if you could respond to this request via my email as well as posting on here please. (I am unlikely to be able to get back to this post and see your response, due to my dimness). I would greatly appreciate it if you can.
So… to the mattress topper. For many years now I have had a memory foam mattress, but due to a house move my original bed didn’t fit in my new bedroom. So I have bought a complete new bed and mattress. They were both fairly expensive and are only 3 months old. The base is one of those that opens/lifts up for storage. I stupidly didn’t buy a memory foam mattress this time and it is giving me untold problems with ongoing neck and shoulder problems, but I find I also have to support both sides of my waist with small cushions when I’m in bed. In my opinion this mattress is too soft and my issues are only going to get worse, not better.
Is there a mattress topper out there that will help to firm this mattress up that doesn’t cost the same as a half decent memory foam mattress?
Thanks very much in advance for any advice you may have and I really would appreciate an email to either respond to this question or at least send me back to this link.
Thank you for your kind words!
Normally, you will get notification of my reply in your email.
In that article, you can find top rated medium-firm to firm toppers which can help to make your mattress firmer. If you want more firmness (if your existing mattress is too soft), you should buy a latex topper, because naturally, latex is firmer than memory foam (but they are more expensive).
Hi, I clicked on the link for the latex mattress topper as you suggested and the description and reviews all indicate that it makes your mattress softer not firmer.
My situation is basically that I have back pain and my boyfriend and I have a brand new mattress that he loves and my back is hurting. So I figured if I could get a mattress topper for my half of the bed, that would solve my problem without disrupting his sleep.
Yes, latex toppers can both help to make your mattress softer or firmer (I mentioned both in that article). It depends on the firmness of the topper your choose: soft, medium-firm or firm. A soft topper will make your mattress softer. A medium-firm or firm latex topper will help to make your mattress firmer and help relieve back pain.
I also wrote an article about mattress topper for back pain here: https://www.thebestmattresstopper.com/best-mattress-topper-for-back-pain.html
I have a mattress with an attached pillow top. I feel like I can’t clip it for that reason, but would the plywood help? My husband and I wake up every morning with back pain. Buying a new mattress is not in our budget at this time especially being the holiday season. Any suggestions would be appreciated, thank you!
Sorry for late feedback.
You should check your bed foundation, if it’s not good then using plywood can help a little.
You can consider buying a mattress topper too, an affordable mattress topper can improve your mattress. Take a look at our article on choosing mattress topper for back pain here: https://www.thebestmattresstopper.com/best-mattress-topper-for-back-pain.html
Layla Paker says
Hi, Thanks for your the article. Everyone knows that a good mattress is important for your sleep. When we have used it for a while, it lacks softness, which causes problems such as back pain, knee pain, waking up at midnight. Make mattress firmer is a temporary solution, I wonder if I should change the mattress? I am in need some information. Can you give me a tutorial? Thank you very much, have a nice day.
I bought a king size ottoman bed with a memory foam mattress but I have not been able to sleep on it as its too soft I have neck and back pains. I cant get up form it its too soft and very uncomfy,
Could you please help?
Did you read the article and try our suggestions?
You can buy a medium-firm or firm topper to firm up your mattress. A good mattress topper can help relieve back pain too. Read more about choosing mattress topper for back pain here: https://www.thebestmattresstopper.com/best-mattress-topper-for-back-pain.html
Which would sleep cooler, a firm memory foam topper or a firm latex topper? I have a new mattress that is too soft and does not allow me to turn over easy, but do not want something that adds heat as i like to sleep cool.
A firm latex topper is cooler. Generally, latex and gel-infused foam are top cooling materials.
Barbara watkins says
Thanks for this information. My frequent guest requires a firmer bed than that provided by my memory foam, which is almost new. I will look for a firm topper. What a relief to not buy a whole new mattress!
Thank you so much for this helpful article. I have been given a bed by a friend, but the mattress is a soft mattress and is far too soft for my partner who likes and needs a firmer mattress. Will a Latex mattress topper help firm up the mattress enough for him?
Yes, a latex topper can help.
Great article, just remember to use a mattress encasement on any mattress to keep it protected from bed bugs, spills, viruses, dust mites, allergens, etc.
I sleep on the floor and my back feels wonderful.
Brian M Salazar says
Your article was super useful. I looked into the latex topper but the brand you suggested (Ultimate Dreams) is not available in firm for a king size bed. Another brand (Pure Green by SleepOnLatex) is available and sounds promising. However, it doesn’t seem to come with a cover. In your experience, is a cover required?
My only other concern is if the bed sheets will fit with such thickness. I definitely need Firm though bc my tempurpedic has somehow become too soft since we got it a few years ago.
Butch Armstrong says
My issue is that I have a nice mattress that is only a couple of years that is soft for me since I have arthritis in my hips. The problem is now I have my girlfriend living with me, and she needs a firmer mattress. What do you think about cutting a mattress topper in half, or purchasing a twin topper to go on my queen bed. I fear that would put her side of the bed higher than mine. I really do not want to spend 1000.00 for a new adjustable mattress since mine is not old.
Hi Butch Armstrong,
Yes, you can put a topper on one side of the bed to adjust the firmness of your mattress. You can buy a thin topper (about 2 inches) to reduce the height difference.
Or, you can also try a medium firm topper to see if it’s comfortable for your hip. A medium firm topper can be a good solution for both of you.
Amber Elliott says
I am having a hard time finding a firm mattress topper. Do you recommend one? I bought my daughter and son n law a new bed and it’s not firm enough. So they are not using a 900 mattress.
Hi Amber Elliott,
Robert VandenHeuvel says
I fixed a Tempur-Pedic soft mattress that was too soft by adding a latex topper underneath it. I weigh 260 pounds and I have back deformities. The soft mattress felt great in the store but was causing pain at home, so I followed the recipes posted here and on Amazon and bought a latex topper 2″ and put it under the existing mattress on top of the box spring. It helps about 90% and the rest of the aches and pains are tolerable. I won’t be moving the topper to the upper side. This arrangement already works so well, and for only about $200
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How To Make A Mattress Firmer
A few ways you can make a soft mattress firmer and more supportive.
Before we begin, let’s first firm a few things up (get it). All jokes aside, this post is designed to be a helpful guide for you to firm up your existing mattress. Let’s get to it.
Why You Might Need A Firm Bed
There are many reasons why you might need a firmer mattress. Your bed may have simply arrived a little softer than expected. Also, some mattresses tend to get softer with time, as you break them in. If you have a back injury or some back pain, your doctor may have recommended that you sleep on a firmer surface. Or maybe your partner moved in, and they need a firmer mattress. Whatever it is, we’re here to help.
Let’s first go over some reasons why having a firmer versus a softer bed can be so important, and then we’ll talk about some options for making your mattress firmer.
Why Firmness Level Is Important
When we talk about firmness here at the Slumber Yard, know that we are doing so in a relative manner, as firmness is a term that is relative to weight. Basically, the less you weigh, the more you lay on top of a mattress, sofa, or any other surface for that matter. When you’re laying more on top of a surface, instead of sinking down in it, it will feel firmer to you. Because of this, petite people might find more mattresses feel firm to them.
On the opposite end of spectrum, the more you weigh, the more you sink into a mattress or other surface. Because you’re sinking down into the material more, the surface will feel softer. Heavier people might find more mattresses feel softer to them, and may have a more difficult time finding a firm enough bed. In some cases, though, we have found that heavier people will sink right through the comfort layers of a mattress and will settle more on the poly foam or coil base layers, which actually make the bed feel firmer. This isn’t good for your spine though.
Your sleeper type is also important when considering the firmness level you need in your mattress. Side sleepers tend to need a softer mattress that will accommodate their curves, instead of fighting against them and possibly limiting blood flow. Back and stomach sleepers will need a firmer mattress that will keep their spine in proper alignment while they sleep. Back and stomach sleepers shouldn’t have their hips or shoulders sinking into the bed too much, as this will cause the spine to be in an arched position, which can lead to back aches or other problems.
Plank is a firm mattress
Having a firm bed can also be better for your health. Remember, you sleep on your mattress for (hopefully) eight hours every night. Over the course of a lifetime, that’s a third of your life spent sleeping. Keeping the spine in proper alignment, whether sleeping on your back or on your side, is very important for the overall health of your body. This study even explores the concept that firmer bedding can reduce back pain, improve sleep quality, and decrease overall stress.
Keep all this in mind as we explore the different options you have when it comes to making your mattress more firm.
Options To Increase Firmness
Trial period.Many online mattress brands have trial periods, so that you can really get to know your new mattress before you commit. Most companies offer a 100-night trial period, but others, like Nectar for example, have year-long trial periods. Check to see if your mattress is still within its trial period, because you might be able to return the bed for a full refund, and most of the time the company will come remove the mattress for you, also free of charge. You could also try contacting the company and see if they can help you. Novosbed will even send you a Comfort+ Kit, which is a free foam topper, if you feel the firmness of the bed isn’t quite right for you.
Try placing your mattress on the floor.If that makes it feel firm enough for you, you could either go for a cool college kid vibe and leave it there, or you can try slipping some plywood boards between your mattress and the bed frame. This will add some extra firm support and possibly harden your mattress.
Check your box spring.Box springs can wear out with prolonged use. When they lose their strength, they provide less support for your mattress than they should, which in turn may make your mattress feel softer. Replacing a box spring is usually much less pricey than replacing a mattress, and can help to harden up your bed.
Replace the worn out layers.More and more companies are manufacturing their mattresses with different layers of material, so it’s easy to switch out the ones that are more damaged. This is also a more affordable way to make your mattress firmer. Just make sure your mattress has a removable mattress cover and you’re not
Dampness.Your bed can become soft from absorbing moisture from the air. This is common in humid areas or if you live close to the beach. If you think this might be the problem, just take your bed and lay it in the sun, and let it dry out for the day. This should not only firm up your mattress, but the sun should also kill off any bacteria, mold, and germs that may have occurred from the dampness. If you’re super worried about a contaminated mattress, you can also pay for a professional cleaning, but make sure to try this first.
Mattress topper.I know, you’re probably thinking, aren’t mattress toppers suppose to make beds softer? But there are tons of great mattress toppers you can find on Amazon that will make your bed firmer. We suggest a dense memory foam or a latex one. Latex is a natural foam material made from the sap of rubber trees, and its known to be pretty firm and responsive. They have synthetic latex options, as well, which are usually cheaper. Toppers are usually around 2”-6” thick, so they can make your bed decently thicker, or just a little bit thicker, if that’s what you prefer. Also, mattress pads tend to be thinner and make mattresses softer, so look specifically for a topper.
Consider your room temperature.Some materials, like 100% memory foam or airy polyurethane foam, can be temperature sensitive. If you leave them in a cold room they We’ve even heard of pure memory foam freezing solid if left in a super cold climate! Try adjusting your thermostat in your bedroom to a lower temperature, or even leave a window open and get the fan going and see if that firms up your bed a bit. Likewise, a warmer temperature might make your bed softer.
Rotate or flip your mattress.Sometimes simply rotating your bed so that the heavier parts of your body lay in different spots can help. We always recommend that, no matter what kind of mattress you have, you rotate it seasonally to help prevent against sagging or impressions. If your bed is two-sided, you can also try flipping it to make it firmer. Just double check first that it’s a flippable mattress. Some beds, like the Plank for example, come with two different firmness levels on each side. If there aren’t different firmness levels, the unused side will still often be firmer.
Nest Flip is a double-sided mattress
If all else fails, get a new mattress. As we explained above, the firmness of your bed is very important for your spinal health, and to prevent against body aches and stiffness. This is especially true for strict back or stomach sleepers. Also, having a worn out bed that’s been around too long is just not great for your body. If you’ve had your bed for over 10 years and it’s much softer than when you first got it, it might be time for a new mattress anyway. You can check out our list of Best Firm Beds or Best Beds for Back Sleepers if you want some help figuring out which bed might be best for you.
How To Fix A Sagging Mattress
Simple tips and tricks to improve mattress support and fix your sagging bed.
Do you ever wake up with a sore back, hip pain, or a stiff spine? Don’t blame this on old age just yet—it’s most likely your mattress. While we as a society often overlook back pain because it can be caused by so many different things, waking up with back pain is a major sign that it has something to do with your mattress, especially if you notice the pain or stiffness fades over the course of the day.
Our first recommendation is to look for sagging spots in your mattress. A sagging mattress causes spinal pain or stiffness because it throws your spine out of proper alignment. Remember, we spend a third (give or take) of our 24-hour day sleeping. That’s six to nine hours that your spine could be laying out of whack, which can affect blood flow and your muscles.
Example of a sagging mattress
To check if your mattress has sagging areas, try laying something flat like a yardstick across the top surface of your bed and look for gaps underneath. Common areas are usually where heavy spots of the body, like the head, hips, and shoulders, lay. Also run your hand over your mattress and feel around for areas that are lumpy, hard, or where there may be areas where your springs feel different or are poking through. If you feel any of these, you either need to fix the mattress or get a new one.
How To Fix A Memory Foam Mattress
If your memory foam mattress is sagging, first try rotating the bed 180 degrees or flip it if it’s a double-sided mattress. This will make it so that your body applies pressure in different areas. This can sometimes even out the foam by redistributing weight.
Layla is a good example of a flippable mattress
If that doesn’t work for you, consider a memory foam mattress topper. A thick topper can help to fill in slight indents, and also doesn’t change the feel of your mattress. There are tons of memory foam toppers available in different thicknesses and they come with different features like cooling, pressure relieving, or even scented.
How To Fix A Pillow Top Mattress
Most of the time with pillow top mattresses like Avocado for example, they can’t be flipped, so the only answer is to rotate the bed. The same idea applies; your weight will be redistributed and can hopefully even out the pillow top.
If that doesn’t work, try sliding a 1” thick wooden board between your mattress and box spring or bed frame where it’s sagging. The board will act as an additional layer of support, which will hopefully even out the bed and help to reduce the sagging. Keep in mind that it can possibly make your mattress feel firmer, though.
You could also try checking your bed’s box spring to see if it has any broken or weak spots. A bad box spring can’t support a mattress properly, which can lead to sagging. You can test your box spring by simply pushing your hands on it, or you could even grab your small children and have them walking around on it a bit.
How To Fix A Sagging Mattress With Plywood
If your mattress has a slight sag, or you notice it might need more support in a certain area, in some cases you can fix it with plywood. Just place the plywood between your mattress and your box spring, in the area where you need the fix. If you don’t have a box spring and rest your bed on your bed frame, you might need to double up on the plywood to make sure it remains straight and sturdy. Plywood won’t completely fix the issue but it should at least help.
Plywood can help (sometimes)
If you just want a little more support from your mattress overall, cut your plywood so that it’s the same dimensions of your mattress, and then place the plywood under the entirety of your bed.