Mattress Fillings Explained

What's Inside Your Mattress?

Understanding what goes into a mattress can make a real difference when it comes to choosing the right one. Here's our honest guide to the most common fillings and what they mean for your sleep.

Pocket Springs

Pocket springs are individual springs sewn into their own fabric pockets, allowing each one to move independently. This means the mattress responds to your body shape rather than moving as one unit — which is particularly beneficial if you share a bed, as movement on one side is far less likely to disturb the other. This is often referred to as no roll-together, and it's one of the most practical advantages of a pocket sprung mattress.

Pocket springs are also more supportive than open coil or Bonnell spring systems, which use a single interconnected wire unit. Because each pocket spring works independently, they provide more targeted support across the full surface of the mattress — particularly around the heavier areas of the body such as the hips and shoulders.

When it comes to spring count, it matters — but it's not the whole story. What really determines how a mattress feels is the combination of the spring unit and the comfort fillings placed above it: what those fillings are, how generously they're used, and how they're layered. A well-made mattress with a thoughtfully constructed filling system will often outperform one with a higher spring count but thinner or lower-quality comfort layers. It's the complete package that counts.

Memory Foam

Memory foam is a pressure-sensitive material that moulds to the contours of your body in response to heat and weight. It's particularly popular with those who suffer from joint or pressure point discomfort, as it distributes weight evenly across the surface.

Memory foam can provide a "sinking" feeling as it slowly conforms around you. For most people this feels cosseting and comfortable — but for those who find it difficult to turn over in bed, this sensation can make movement harder, as the foam holds its shape around you rather than springing back immediately. If mobility during the night is a consideration, it's worth trying a memory foam mattress in store before committing.

One thing to be aware of: memory foam can retain heat. If you tend to sleep warm, look for mattresses that combine memory foam with breathable natural fillings or open-cell foam structures designed to improve airflow.

Natural Fillings

Natural fillings are used in the comfort layers of many higher-end mattresses and are prized for their breathability, durability, and feel. Each has its own properties:

  • Wool is naturally temperature-regulating, wicking moisture away from the body and helping to keep you cool in summer and warm in winter.
  • Cotton is breathable and hypoallergenic, offering a clean, firm feel.
  • Cashmere and silk add a luxurious softness and are often found in premium mattresses.
  • Horsehair is one of the most traditional fillings, prized for its durability and natural springiness. It's resilient, breathable, and tends to be found in the finest hand-crafted mattresses.
  • Alpaca is an increasingly popular natural filling, known for being exceptionally soft, lightweight, and naturally hypoallergenic. It's also highly temperature-regulating, making it a good choice for those who sleep warm or cold.
  • Camel fibre is a luxurious and less common filling with excellent insulating properties. It naturally wicks moisture and regulates body temperature, offering a warm yet breathable sleeping environment.
  • Hemp and flax (linseed) are plant-based natural fibres that are breathable, durable, and naturally resistant to bacteria and mould. They tend to offer a firmer feel and are a sustainable choice.
  • Bamboo is a soft, breathable fibre with natural moisture-wicking properties. It's often blended with other fillings and is popular for its cooling qualities and eco-friendly credentials.

Mattresses with natural fillings will often require turning (not just rotating) to ensure even wear — but they tend to be exceptionally durable when cared for properly.

Latex

Latex is a naturally derived material that offers a responsive, buoyant feel — quite different from the slow-response sink of memory foam. It's naturally hypoallergenic, resistant to dust mites, and highly durable.

Natural latex is breathable and tends to sleep cooler than synthetic alternatives. It's a good option for those who want pressure relief without the “stuck” feeling that some people associate with memory foam.

Reflex Foam

Reflex foam (also known as high-resilience or HR foam) is a denser, more supportive foam that springs back quickly when pressure is released. It's often used as a support core in foam mattresses or as a transition layer beneath softer comfort fillings.

It's a practical, durable material that holds its shape well over time — and is often found in mattresses at the more accessible end of the price range.

Hybrid Mattresses

Many of the mattresses we stock are hybrids — combining a pocket spring support core with foam or natural comfort layers above. This approach aims to give you the best of both worlds: the responsive support of springs with the pressure-relieving comfort of foam or natural fillings.

Hybrids tend to be a good all-round choice, particularly for couples with different preferences.

Still Not Sure?

The honest answer is that no guide can replace lying on a mattress. Please come and visit us in King's Lynn or Wisbech — there's free parking at both stores, and our team are here to help you find the right fit without any pressure.

Not sure which firmness is right for you? Read our guide to choosing the right mattress.