New Memory Foam Mattress (How to Treat Yours Right!)

Memory foam mattresses mean your mattress comes to you compressed in a box. That squeezed mattress will expand, as if by magic, into a comfortable full-sized mattress.

Before mattresses in a box, delivering a mattress took a large truck and at least two handlers to get it where you needed it.

Of course, you will still find large mattresses delivered by a small team of handlers but they are for mattresses designed with springs in them. Unlike memory foam mattresses, these cannot be compressed, rolled, or compressed.

Can I Sleep on My New memory Foam Mattress Right Away?

On arrival, you unbox and release the mattress from its packaging and leave it flat on the floor to expand. Typically, waiting for 24 to 48 hours would give the mattress the time it needs to reach its specified dimensions.

Failure to wait may void the warranty.

The memory foam mattress needs to expand to give you the depth of comfort and support for a restful night’s sleep. Besides that, if there are any defects in the mattress, they won’t show up until the mattress expands fully.

Defects include cracks, tears, splits, and incomplete expansion along with any damage or staining in transit.

You cannot sleep on a memory foam mattress as soon as you take it out of the box – it is like an uninflated airbed, not enough thickness or support. However, you can sleep on the mattress before the 48-hour window expires when the memory foam mattress expands sufficiently to be useable.

How Long Does It Take for a Memory Foam Mattress to Fully Expand?

Depending on the manufacturer, you allow between 24 and 48 hours for full expansion of the mattress.  This time frame is the manufacturer being cautious. Sometimes a foam mattress will take longer to expand than similar mattresses.

After four to six hours, your mattress expands to 90% of its specified dimensions. Another four to six hours, and it is expanded fully or close to it.

Degassing (also referred to as off-gassing) takes place in the first few hours.

Degassing sounds potentially dangerous but is merely allowing the volatile organic chemicals (VOCs) to evaporate. These give you that new smell associated with plastic sealed in a bag.

Your mattress arrives in a sealed bag, the gasses given off by foam have nowhere to go and release in a burst into the air, and you notice them. It is no different whether you’ve bought an ordinary memory foam or a gel memory foam mattress.

Regular air changes through natural ventilation are a good idea because many household products add chemical gasses into the room air. The amounts are tiny, but you still want to remove them from an enclosed room and replace them with fresher air.

Measure your mattress after a day or two to check that it has finished expanding. If it is not done expanding by the end of a week, then there is an issue, and you want to get in touch with the seller for a replacement.

Manufacturing defects can occur, so getting a replacement unit shouldn’t be an issue.

What Happens If You Sleep on a Memory Foam Mattress Too Early?

If the mattress is still expanding when you sleep on it, you don’t get all the support it is capable of giving you. Nothing terrible happens to you or the mattress just because you sleep on it before the end of the advisory time.

What happens if you sleep on a memory foam mattress before 24 hours is that you don’t rest as well as you will on a fully functioning memory foam mattress.

Your body heat and weight help the memory foam activate and expand. Still, sleeping on the mattress before the time elapses may void your warranty.

Sleeping on the memory foam mattress does not cause defects, so if the mattress is faulty, you will ask for a replacement even if you slept on the mattress before 24 hours elapse.

How to Make a Memory Foam Mattress Expand Faster?

You’ve unpacked your memory foam mattress, and you can’t wait for one or two days before you need to use it, is there any way to speed up the expansion process?

Compressing and rolling the memory foam mattress involves tons of pressure and heavy-duty rollers to squeeze out all the air. The air increases volume, and by removing it, you can pack the mattress in a box.

In order to make a memory foam mattress expand faster, you need:

  • Increased airflow
  • More heat
  • Added pressure

Increase Air Flow

Air going back into the mattress causes it to expand to its original dimensions. Any way of speeding the flow of air into the mattress decreases the expansion time, and you speed up memory foam off-gassing.

You can get increased airflow by opening a window and door or using a fan to create a wind across the surface of the mattress. This action supplies more available air for expanding the foam, as well as ensuring the VOCs from off-gassing do not stay trapped in the room.

Turn up the Heat

When you get onto a memory foam mattress in a cold room, it feels firmer. As your body heat warms the foam, it gradually softens.

Memory foam is sensitive to temperature – turn up the heating in the room, and this will promote quicker expansion.

Don’t put a heater close to the foam mattress though. That is potentially damaging to the structure of the foam.

Aim to raise the room temperature rather than heating the mattress directly.

Apply Some Pressure

This next step may seem strange – roll around or walk over the memory foam mattress.

Your body heat and pressure loosen up the foam and help it to expand. You are squashing and releasing the foam.

Although you are displacing the air when you compress the mattress, you are also encouraging it to suck more air in – like a bath sponge when you squeeze and release underwater, but the same idea on a bigger scale.

If you do nothing but unpack your mattress and lay it out, it will be 90% expanded in around six hours. The above measures help to decrease the expansion time, but it is still going to take hours for full expansion – there is no instant fix.

Do You Need to Break in a Memory Foam Mattress?

New shoes are stiff and rigid until you break them in, but what about memory foam mattresses? Does the same apply? If so, how do you break in a memory foam mattress?

The easiest way to break in a memory foam mattress is to sleep in it. How long does it take to break in a memory foam mattress?

It’s not so much you are breaking in a memory foam mattress as it completes its full expansion, and you get used to how it feels when you lie on it.

Over time you got used to your old mattress, and now your new mattress feels different. If it is your first memory foam mattress, the way it reacts to your body feels unfamiliar. After a week, your mattress is expanded and will feel familiar and comfortable.

Your memory foam mattress will feel firmer in a cold room than in a warm one, but your body heat lets it soften and respond to your weight. If you prefer to get into a softer bed, use a hot water bottle for about an hour before you want to get in bed.

Why Won’t My Memory Foam Mattress Expand?

From one manufacturer to another, you are typically asked to wait for 24 to 48 hours before sleeping on it.

However, the mattress would usually regain 90% of its original form in 4 to 6 hours once you unpack the mattress.

A compressed foam is much like a restrained spring with all the pent-up energy inside it, simply waiting to release that energy and take its full form again.

If you do not see a near-full expansion of the memory foam mattress in the initial 4 to 6 hours of unpacking and laying it flat on the floor or bed base, or if you see clear uneven expansion across the surface of the mattress in that time frame, the mattress is likely defective.

What If You’ve Bought a Memory Foam Mattress Topper?

Perhaps you have an existing mattress that you don’t sleep very well on but it’s not time to discard just yet.

In this case, a memory foam mattress topper or a gel-infused topper would be useful to increase the comfort level you’re looking for.

But, can you sleep on a memory foam mattress topper the first night? Not all new mattress toppers come with instructions on when you can start sleeping on it.

Although the manufacturers generally specify 24 to 48 hours for full inflation, it will suffice to wait a few hours before sleeping on a memory foam mattress topper. As such, it is fine for you to sleep on your new memory foam mattress topper the first night but be prepared that it will become more comfortable to sleep on in the following nights.


You can sleep on a memory foam mattress before it is fully expanded (after about six hours), but you get the best restful sleep after a week.

At the end of a week, the mattress should be fully functional and broken into your preferred sleeping position.

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