What Happens If You Don’t Let Mattress Rise

Learn why letting a boxed mattress decompress matters, what happens if you skip it, and practical steps to promote proper rise for comfort and longevity.

Mattress Buyer Guide Team

February 19, 2026·5 min read

Mattress Memory Foam Longevity Durability

Decompression Guide - Mattress Buyer Guide — Photo by Pexelsvia Pixabay

mattress rise (decompression)

Mattress rise is the expansion and normalization of a shipped mattress after unboxing, as foam layers and springs regain their intended shape.

Why decompression matters

What happens if you don't let mattress rise is more than a minor delay in comfort. When you unbox a mattress, its foam layers and springs are compressed and shipped in a compact package. They need time to expand back into their final shape, settle evenly, and remove the creases that form during packaging. Skipping this step can leave you sleeping on an uneven surface with high spots and low spots, which can create pressure points and disrupt spinal alignment. The Mattress Buyer Guide team notes that proper decompression improves edge support, reduces motion transfer, and helps the top surface become uniformly comfortable across the entire bed. Temperature, humidity, and the mattress's core materials influence how quickly it rises, so results vary by model. If you rush into sleep, you may not experience the full feel the manufacturer designed, and you could misjudge the mattress's true firmness. In many cases, giving the mattress time to rise also lets any odors from manufacturing dissipate, contributing to a healthier sleeping environment. Understanding the decompression process helps homeowners and renters set realistic expectations about new purchases and their first weeks of use.

What happens if you skip the rise

Skipping the rise can leave you with a surface that doesn't reflect the final feel. In foam mattresses, the top layers may remain compressed and create firmness variations, leaving a firmer zone near the center and softer edges. In hybrid or innerspring designs, the core coils may stay compressed in a way that reduces the uniform support across the sleep surface. These effects can lessen after the mattress fully expands, but sleeping on it early can cement impressions or cause temporary sagging while you move. Additionally, you may notice lingering chemical odors from packaging or adhesives. Off-gassing is typically more noticeable with rapid use, so allowing time for this to subside contributes to a cleaner sleep environment. The Mattress Buyer Guide team recommends not rushing the setup; instead, consider giving the mattress a dedicated period for rising before moving it into your preferred sleeping position. With a little patience, the bed will become more comfortable and supportive as it reaches its designed performance.

Factors that influence decompression time

Several factors determine how quickly a mattress rises to its final shape. The type of core material, such as memory foam or latex, the presence of a traditional coil system, and the thickness of the comfort layers all affect expansion. Room temperature and humidity play a role; cooler rooms can slow expansion whereas warmer, well-ventilated spaces tend to support faster recovery. The base on which the mattress sits also matters; a soft or uneven surface can hinder even expansion and cause localized creases. Finally, how the mattress was stored before unpacking matters; if it sat tightly rolled for an extended period, the expansion may take longer. The Mattress Buyer Guide team suggests planning for a decompression window that reflects your specific model and environment, and checking the manufacturer guidance for any model specific notes. For many shoppers, understanding these factors helps set realistic expectations and reduces frustration during the first days of use. Sources from Sleep Foundation and CDC sleep guidance corroborate the general idea that environmental conditions influence comfort and recovery times.

Practical steps to promote even rise

From unboxing to placement, you can help ensure a smooth decompression process. Start by removing the packaging as soon as you can and placing the mattress on a solid, flat foundation. If your frame has slats, ensure they are evenly spaced and supportive. Give the mattress plenty of space to breathe by placing it in a well ventilated room and avoiding direct heat sources. Allow it to rest undisturbed for the majority of the day or night, and then rotate or flip as recommended by the manufacturer after the initial rise period. Some models benefit from gentle turning to promote uniform shape recovery, while others should be left as is until fully risen. Keep an eye on signs of full expansion, such as the surface appearing uniformly flat with no noticeable creases. Remember that patience during the decompression period pays off in long term comfort and durability. The Mattress Buyer Guide team notes that following the model specific guidance can help avoid issues and maximize the lifespan of your new bed.

Off-gassing, odors, and air quality

New mattresses often release a faint odor as volatiles escape from foams and adhesives during the decomposition period. This off gassing is normal for many materials and typically diminishes as the mattress expands and air circulates. To minimize smells, keep the room ventilated, use a window fan if possible, and avoid sleeping on the mattress until it has had a chance to rise and air out. If odors persist beyond the initial decompression window or you experience irritation, consult the manufacturer's guidelines and consider a temporary protective cover. The Mattress Buyer Guide team recommends patience and proper airflow to maintain air quality while the mattress settles into its final form.

When to contact the manufacturer or consider exchange

If after a reasonable decompression period the mattress still has pronounced deformities, excessive odor, or fails to reach the expected firmness and support, reach out to the manufacturer for guidance. Check the warranty terms and any model specific conditions related to unpacking and use. In some cases, you may be advised to return or exchange the product if it does not meet the stated specifications after the decompression window. Throughout this process, document symptoms like persistent creasing or uneven feel and reference your unboxing notes. The Mattress Buyer Guide team suggests evaluating not only comfort but also durability indicators such as edge support and overall symmetry when determining next steps. With clear communication and a careful assessment, you can decide on the best path for your sleep health.

FAQ

Is it safe to sleep on a mattress before it fully rises?

Sleeping on a mattress before it fully rises can feel uncomfortable and may not reflect its intended comfort. It is generally best to wait until you observe full expansion or follow the manufacturer's recommendations.

Do all mattresses require decompression after unboxing?

Most boxed mattresses, especially foam and hybrid types, benefit from decompression. Innerspring models may expand quickly, but following the manufacturer guidelines is still recommended.

Can you speed up decompression with heat?

Heat can aid expansion for some materials, but applying direct heat or sun exposure can damage materials or alter the feel. Always follow the manufacturers instructions.

What about memory foam off-gassing?

Off-gassing is common with memory foam and other foams. Ensure good ventilation and air circulation during the initial decompression period to minimize odors and irritation.

How long should I wait before sleeping on it?

There is no universal duration. Wait for your model’s decompression period, and if not specified, give it a day or two to fully rise and aired out.