How long does a mattress in a box take to expand and when can you sleep on it?

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Gone are the days when traditional mattresses hauled in by the delivery team were your only option. Now you can choose ones that are packed and shipped in a box, delivered to your door, and are easy to move around and unwrap.

With this practicality in mind, It is no wonder many mattresses in a box have secured top spots in our guide to this year’s best mattresses for all sleepers. Before choosing a new mattress in a box, it is important to know that, unlike conventional mattresses, these take time to expand.

The time they take to fully expand differs depending on the brand. A question we often come across is whether you can sleep on a mattress that is still expanding. Here, we'll look into why they need to expand, and how long you can expect to wait for each brand.

What is a mattress in a box?

As the name suggests, these mattresses are compressed using a machine, tightly rolled and packed into a hard cardboard box for shipping. They are becoming increasingly popular due to the convenience of transport and moving.

While mattresses in a box are usually associated with memory foam beds, hybrid varieties have also entered the picture now. It is true that most of these are budget-friendly, however, this does not translate to inferior quality.

All options listed in our guide to this year’s best mattresses in a box have been tried and tested, with our reviewers reporting superior comfort and high-rated performance.

Why does a mattress in a box need to expand?

Mattresses in a box are compressed with specialist machinery and tightly wound with heavy duty plastic. When you unbox your mattress, it requires a certain amount of time to expand fully before it can be slept on.

This is because you need to allow time for the air to get back into the mattress between its different foam layers, which were pressed and squashed during the compression process.

The air slowly helps fluff up the bed and regain its original shape. Depending on the brand of the mattress, the materials used and the thickness of each layer within the mattress, the time it takes to expand may differ considerably.

Surprisingly, the humidity and temperature in your room can also influence the time it takes for your mattress to expand.

How long a mattress in a box takes to expand by brand

Typically mattresses in a box take anywhere between 24-72 hours to expand. But, as we've mentioned, the type of bed and the construction process of each mattress determines the exact expansion time for each brand. Here are a few popular picks and how long you can expect to wait.

Nectar

While it’s one of the best rated brands for mattresses in a box, Nectar mattresses are known to take about 72 hours to expand.

This is no surprise as the Nectar Memory Foam mattress is 12” inches tall with five-layers of foam, gel infusion and a quilted cover. The medium firmness and hi-core memory foam adds to the overall thickness of the bed and lengthens the time it takes to expand.

Helix

According to the team at Helix, its mattresses take just 35-40 minutes to fully expand which is one of the lowest expansion periods for a mattress in a box.

With a solid 6 out of 10 for firmness, the Helix Midnight Luxe mattress is included in our list of best mattresses in a box and was rated as an excellent option for side sleepers by our testers in the Helix Midnight Luxe mattress review.

DreamCloud

These mattresses take up to 72 hours to fully expand. DreamCloud mattresses range from 14 to 16 inch thickness depending on the model. These are compressed and then vacuum sealed before being packed into hard cardboard boxes for shipping.

Known to be firm and supportive beds, our expert testers for the reviewed the DreamCloud Premier Hybrid review said it mimics hotel-like quality and comfort.

Purple

These take about 24 hours to expand. This is because Purple's gel-hybrid memory foam mattress is on the thinner side being under 10 inches deep.

In fact, in our Purple Original mattress review, our testers underlined it as one of the shallowest beds they’ve slept on, which comes under the recommended 10 inches for adults. However, it does still deliver adequate support and comfort.

Siena

The brand says that while you can sleep on the bed after a few hours of expansion, it takes approximately 72 hours for the mattress to fully expand.

The Siena is a 10 inch-3-layer mattress with a 2”inch gel infused polyurethane memory foam comfort layer, 4” of support foam and a 4”inch firm standing foundational base.

What happens if you sleep on a mattress that’s still expanding?

Can you really sleep on a mattress that is still expanding? The simple answer to this would be ‘no’. Mattress companies generally advise against using your bed before it fully expands.

This is because exerting pressure while the foam is reverting to its original shape can hinder the process. The layers may take longer to expand and even suffer lasting damage before your trial period starts. If you don't leave your mattress enough time to fully expand before laying on it for too long, it can cause your mattress to sag, reducing its quality.