What happens if you sleep on a new mattress right away?

September 30, 2025 •

4 min read

Most mattress manufacturers suggest waiting 24 to 72 hours for a new bed to fully decompress after delivery. So, what happens if you sleep on a new mattress right away, and can it cause any issues for your sleep or the mattress itself?

Quick Summary

Immediate use can lead to uneven expansion, a temporary odor from off-gassing, and an adjustment period for your body. Discover how patience can lead to a more comfortable and supportive sleep experience as the mattress materials and your body acclimate.

Key Points

Expansion is Crucial: Mattresses delivered in boxes, especially memory foam and hybrid types, require 24-72 hours to fully expand and achieve their intended comfort and support.
Expect Off-Gassing: A new foam mattress will release a harmless, but sometimes unpleasant, chemical odor (VOCs) that dissipates faster with proper ventilation.
Embrace the Adjustment Period: Your body may feel stiff or sore for the first few weeks as it adapts to the new support and spinal alignment, which is completely normal.
Immediate Sleep Won't Cause Permanent Damage: While you won't ruin the mattress, sleeping on it too soon can result in uneven comfort and a delayed break-in process.
Ventilate and Wait: The simplest way to improve your first night's sleep is to unbox the mattress promptly, open windows, and allow it to breathe before adding bedding.
Body and Mattress Need to Acclimate: Just as a new pair of shoes needs breaking in, both your body and your new bed need time to get used to each other.

Getting a new mattress is exciting, and the temptation to sleep on it immediately is understandable. However, manufacturers and sleep experts often recommend waiting at least 24 hours, particularly for compressed mattresses. This waiting period allows the bed to properly decompress and air out, ensuring you get the optimal comfort and support you paid for. Understanding this process can help you manage your expectations and ensure a smoother transition to better sleep.

The Expansion and Off-Gassing Process

When a mattress-in-a-box arrives at your door, it has been significantly compressed and sealed for transport. This process is convenient for shipping but requires a crucial recovery phase once the packaging is removed.

Expansion: A Matter of Airflow

For foam mattresses and hybrids, expansion is a key step. During compression, air is squeezed out of the foam's cells. Upon unboxing, the mattress begins to 'breathe,' drawing air back in to regain its full size and shape. While some beds will reach 90% of their intended size within a few hours, full expansion can take anywhere from 24 to 72 hours, depending on the material and thickness. Applying pressure too soon can impede this process in specific areas, potentially leading to uneven comfort and support.

Off-Gassing: The 'New' Smell

The distinct smell you notice with a new foam mattress is known as off-gassing. It is caused by the release of Volatile Organic Compounds (VOCs) that were trapped during the manufacturing and packaging process. While generally considered harmless, this odor can be unpleasant and, for some with sensitivities, may cause mild symptoms like headaches or respiratory irritation. Proper ventilation by opening windows and using a fan is the most effective way to dissipate this smell quickly. For those with sensitivities, waiting 24 hours or more in a well-ventilated room can make the first night more comfortable.

How Immediate Use Affects Your Sleep and the Mattress

Sleeping on a new mattress right away won't cause permanent damage, but it can impact your initial experience and the bed's long-term performance.

Uneven Comfort and Support

By sleeping on a mattress before it's fully expanded, you risk applying uneven pressure. This is especially true for heavier individuals and for foam layers that are still decompressing. You might find the surface feels firmer than expected or notice uneven spots where the material hasn't fully settled. This can compromise the bed's ability to contour to your body correctly during the first few nights.

The Body's Adjustment Period

Your body, having grown accustomed to the feel and contours of your old mattress, needs time to adjust to a new, more supportive sleeping surface. For some, switching from a sagging, old bed to a new, firm one can initially cause stiffness or minor back pain as the spine realigns. This is a normal part of the break-in process, which can take 30 to 60 nights for your body to fully adapt.

Potential for Short-Term Discomfort

Beyond the unfamiliar feel, sleeping on a new mattress too soon can lead to short-term discomfort. This includes an unpleasant night's sleep due to the off-gassing odor, or a lack of optimal pressure relief from a partially expanded foam mattress. Waiting gives you and the mattress the best chance for a perfect first night.

A Guide to the Break-in Period

Here's a breakdown of what to expect and how to accelerate the process, followed by a comparison table of mattress types.

Tips to expedite the break-in process:

Walk on it: Gently walking on the surface of the mattress (without shoes) can help soften the materials and speed up the process, particularly for foam and hybrid types.
Increase usage: Spending extra time on the mattress during the day, such as reading or watching TV, adds more pressure and helps loosen the materials.
Add heat: Raising the room temperature can make foam materials more pliable, helping them conform more quickly to your body.
Be patient: Ultimately, the best method is consistent, nightly use. Your body's weight and heat are the most effective tools for breaking in a new bed.

Mattress Break-in Comparison Table


Feature	Memory Foam	Hybrid	Innerspring	Latex
Recommended Wait Time (Pre-Sleep)	24-72 hours for full expansion	24-48 hours for full expansion	Few hours to let air out	Few hours to let air out
Break-in Period (Body Adjustment)	30-60 nights	30-60 nights	2 weeks or less	2 weeks or less
Initial Feel	Often firmer than expected	Can feel immediately plush, but still adjusts	Immediately comfortable, but breaks down faster	Softens quickly to conform
Off-Gassing Potential	Highest, though CertiPUR-US® reduces it	Moderate, depending on foam layers	Minimal, due to coil construction	Low, with an organic rubber-like scent

Best Practices for Welcoming Your New Mattress

To ensure the best possible start, follow these simple steps.

Clear the space: Before unboxing, ensure you have a clean and clear area to set up the mattress.
Unbox immediately: For bed-in-a-box mattresses, unbox promptly after delivery to begin the expansion process.
Ventilate the room: Open windows and use a fan to improve air circulation and speed up off-gassing.
Check the base: Ensure your foundation or bed frame provides proper support, especially if you have a memory foam or hybrid mattress.
Inspect for defects: Use the waiting period to check for any visible defects or damage that may have occurred during shipping.

For more information on the certification of foams, an authoritative resource is the CertiPUR-US® program, which ensures foams are low in harmful VOC emissions.

Conclusion

While technically safe to sleep on immediately, doing so on a new mattress can lead to less-than-optimal comfort due to incomplete expansion, lingering off-gassing odors, and your body's need to adjust. For the best sleep experience, it is highly recommended to follow manufacturer guidelines and give the mattress sufficient time to settle and air out. By being patient and allowing for the natural break-in period, you can maximize your comfort and the longevity of your investment, leading to many nights of truly restful sleep.

Frequently Asked Questions

No, it is not bad for the mattress in a permanent sense. However, sleeping on it too soon can interfere with the full expansion of the materials, especially for compressed foam beds, which might lead to uneven comfort during the initial nights.

The off-gassing odor is typically strongest in the first 24-48 hours after unboxing. With good ventilation, it should dissipate significantly within a few days, though for some people, the smell can linger for a couple of weeks.

Off-gassing is the release of Volatile Organic Compounds (VOCs) from new materials. While the smell is unpleasant, the VOCs released from certified foams are generally considered harmless at the levels present in mattresses, though sensitive individuals may experience mild, temporary irritation.

Mild back pain or stiffness is a normal part of the adjustment period. If your old mattress was sagging, your body adapted to poor spinal alignment. The new mattress, by providing proper support, can cause temporary discomfort as your muscles and spine realign.

To speed up the process, you can consistently sleep on the mattress every night, spend extra time lying or sitting on it during the day, or apply gentle, even pressure by walking on it (without shoes).

You should generally avoid using a thick mattress topper immediately, as it can hinder the break-in process by creating a barrier between you and the mattress. Wait until the mattress is fully settled before adding one.

Most people take about 30 to 60 nights to fully adjust to a new mattress. This allows both the mattress materials to soften and conform to your body and your own body to get used to the new level of support.