What is the support core in a mattress and why is it important?

 Two Tom's Guide sleep staff writers sit on a mattress after testing its support core.
Credit: Future

If you’re shopping for a new mattress, you’ve probably been told to find one that has good support. And whilst you may think that support means how firm a mattress is, it actually means the mattress support core – the unsung hero of a good mattress.

All of the models features in our best mattress of the year guide have excellent support cores, providing the foundation for full-body comfort, healthy spinal alignment and all-over pressure relief. And those aren’t the only benefits, either.

Mattress support cores also dictate the longevity of your mattress, so if you’re noticing dipping or sagging in your current bed, then it's time to upgrade. Now is a great time to buy too, with this year's 4th of July mattress sales in full swing.

Here's everything you need to know about mattress support cores and how they can help you sleep more comfortably.

What is a mattress support core?

The support core is the foundation of your mattress, located in the base and well beneath the comfort layers. The mattress support core provides the structure and stability needed for proper spinal alignment and pressure relief.

Image shows the support core inside a Saatva Classic mattress
Image shows the support core inside a Saatva Classic mattress

Mattress support cores are made from various materials and each offers unique benefits in terms of support, durability and comfort. There are several support core materials used in modern mattresses, including coils, polyfoam (or polyurethane foam), hybrid (coils and foam) latex air and even water.

What does a mattress support core do?

There are five primary functions of a mattress support core that can make your bed feel comfortable and supportive:

1. They add structural support

One of the most important aspects of a mattress support core is the structural support that it offers. Think of the mattress support cores as the back bone of your mattress. Having a good, solid core means that your mattress won’t sag or dip under the pressure of your body weight.

In fact, a good support core will work to ensure even weight distribution and prevent the sleeper from sinking too deeply into the mattress. This is especially important when we are talking about memory foam mattresses because it means you will still get superior contouring and pressure relief but you won’t be left feeling trapped.

A man presses his hand on a mattress to check its support
A man presses his hand on a mattress to check its support

2. They maintain spinal alignment

When we sleep it’s important that we maintain proper spinal alignment. Of course we don’t have any control over our own movements when we are in slumberland so we need to rely on our mattress to help keep our spines in a neutral position.

Proper spinal alignment when we sleep can prevent pain, help up breathe better, promote healthy circulation and improve the overall quality of our sleep. A good mattress support core will help to keep your spine in proper alignment by providing adequate support. This is because the core has been designed to support your body’s natural curves so your spine won’t twist in to unnatural positions.

3. They play a role in pressure relief

Having a good mattress support core means your weight will be evenly distributed across the surface of the bed. This prevents excessive pressure from building up on specific points such as the shoulders, hips, knees and lower back.

When you get pressure in those areas you’ll usually be left with aches and pains when you wake up or you may even just find it hard to get comfortable at night meaning your sleep will be affected.

Side sleeping lie test on mattress_comfort testing
Side sleeping lie test on mattress_comfort testing

Typically, memory foam or latex cores excel at pressure relief as they conform to the contours of the body and cradle pressure points. However, a well-designed support core works well with your mattress comfort layers to create a well-balanced sleep surface. This means you'll feel comfy and supported in every sleep position.

4. Mattress support cores enhance durability

When you have a strong mattress support core this can contribute to the overall lifespan of your mattress. A good support core is the foundation of any mattress and will help to prevent premature sagging and indentations that can compromise both comfort and support.

By bearing the brunt of your body weight and stopping your mattress from dipping or sagging, this simply means your mattress will last longer and you'll get a better return from your investment.

Of course, you still need to look after your mattress and you can do this by regularly vacuuming your mattress and keeping an eye out for any yellow stains on your mattress which may contribute to the decline of your mattress.

5. Some help regulate temperature

If you’re a hot sleeper then you’ll know how difficult it is to sleep when you are overheating. But the mattress support core plays a huge part in how well a mattress dissipates heat to maintain a comfortable sleeping environment.

A woman with curly dark hair lies awake in bed fanning herself because she's too hot to sleep
A woman with curly dark hair lies awake in bed fanning herself because she's too hot to sleep

Different support core materials offer varying levels of breathability and airflow. Innerspring cores which are found within the best hybrid mattresses are usually the coolest as they are naturally more breathable and allow air to circulate freely and stop heat from building up.

Pocketed coils offer superior airflow thanks to their independent movement. Whilst foam cores can trap heat, there have been a lot of advancements in cooling mattress technology so you can now buy open-cell and gel foams that offer better breathability.

What to look for in a mattress support core

If you’re looking for a new mattress, the support core should be a key consideration. The ideal support core for you depends on your personal preferences, sleeping position and body type. Also consider factors such as firmness, and your budget.

If you’re opting for a memory foam mattress, we'd recommend one with high-density foam as they offer better support (and they last longer). If you'd prefer a hybrid or a traditional innerspring mattress, look for thicker gauge coils as these are more durable.

When it comes to the amount of coils, a higher coil count can mean better support but the quality of the coils is what matters most. Pocketed coils, for example, enhance airflow and do a better job at isolating motion compared to traditional open coils.

A 50lb weight is placed onm the edge of the Helix Midnight Luxe mattress in order to gauge edge support
A 50lb weight is placed onm the edge of the Helix Midnight Luxe mattress in order to gauge edge support

Also consider the edge support. Good edge support usually comes from the mattress support core going around the perimeter of the bed. This helps to stop your mattress from sagging and dipping on the edges, which isn’t just good for those who like to sleep on the edge but also if you like to sit on the bed and don’t want to feel like you’re about to roll off while putting on your shoes.

The top 3 mattresses with strong support cores

1. Saatva Classic: was from $1,395 $1,195 at Saatva
The Saatva Classic is the best hybrid mattress in the world right now, boasting a dual-coil support system that offers both support and durability. The base layer is made up of tempered steel coils to provide a solid foundation, and there’s an upper layer of coils that contour your body for exceptional motion isolation and pressure relief – you can read more about this in our Saatva Classic mattress review. I the current Saatva mattress sale you can get a queen size Classic for $1,795 (was $2,095). You'll also get a 365-night sleep trial, lifetime warranty and free white glove delivery. View Deal

2. Helix Midnight Luxe: was from $936.30$702.20 at Helix Sleep
The Helix Midnight Luxe is our top recommended mattress for side sleepers. It brings together individually wrapped coils with luxurious layers of memory and polyfoam for a balanced feel that will suit all type of sleeper. The pocketed coils provide targeted support and our tester during the Helix Midnight Luxe mattress review found it minimized motion transfer. You’ll never pay MSRP for the Midnight Luxe thanks to monthly Helix mattress sales, with a queen size currently reduced to $1,780.40 (was $2,373).View Deal

3. Nectar Premier Copper Mattress: was from $1,499 $999 at Nectar Sleep
The Nectar Premier Copper has a dense support core made of high-quality foam to prevent dips and sagging. It also incorporates a copper-infused layer of foam to regulate body temperature during sleep. As we explain in our Nectar Premier Copper Mattress review, this is an ideal choice for back and stomach sleepers who want a firmer all-foam mattress that sleeps cool. There's up to 40% off the Nectar Premier Copper in this month's Nectar mattress sale, reducing a queen to $1,249 (was $1,949).View Deal