Quick Answer: Open-cell foam allows significantly more airflow than closed-cell foam, with CFM (cubic feet per minute) ratings typically 4-5 times higher in open-cell structures. Open-cell foam sleeps cooler but is softer and less durable, while closed-cell foam traps more heat but provides firmer support. Most modern mattresses use open-cell or modified foam for better temperature regulation. Visit Mattress Miracle in Brantford to feel the difference.
In This Guide
Reading Time: 9 minutes
When mattress companies talk about "breathable foam" or "cooling technology," they are usually talking about cell structure. The foam inside your mattress is made up of millions of tiny cells, and whether those cells are open or closed determines how much air can pass through the material. That airflow directly affects how hot or cool you sleep.
Most shoppers never hear about CFM ratings or cell structure, but understanding the basics helps you cut through marketing language and choose a mattress that actually sleeps the way you want it to. Dorothy, our sleep specialist at Mattress Miracle, walks customers through this regularly. "People come in saying they sleep hot," she says. "Once they understand why, choosing the right mattress becomes much easier."
What Is Foam Cell Structure?
All polyurethane foam, whether it is standard foam, memory foam, or high-resilience foam, is created through a chemical reaction that produces gas bubbles. These bubbles form the "cells" in the foam. Think of it like bread: some bread has big, airy holes (open cells), and some has a tight, dense crumb (closer to closed cells).
Open-Cell Structure
In open-cell foam, the walls between bubbles are broken or perforated, creating an interconnected network of air channels. Air, moisture, and heat can pass through the foam relatively freely. When you press down on open-cell foam, air moves out. When you release it, air flows back in. This is what gives foam its "breathing" quality.
Closed-Cell Structure
In closed-cell foam, each bubble is sealed and self-contained. The walls between cells are intact, trapping gas inside. This creates a denser, firmer material that resists air and moisture movement. When you compress closed-cell foam, the trapped air has nowhere to go, which makes it feel firmer and more resistant.
The Spectrum, Not a Binary
In practice, most foams fall somewhere on a spectrum between fully open and fully closed. Even "open-cell" foams have some closed cells, and most "closed-cell" foams have some open ones. What matters is the overall ratio. Modern mattress foams are typically engineered to be predominantly open-cell, sometimes with intentional modifications to balance airflow with support and durability.
CFM Ratings Explained
CFM stands for cubic feet per minute. In foam testing, it measures how much air can pass through a standardized sample of foam under controlled conditions. It is the most direct measurement of foam breathability.
How CFM Testing Works
The standard test (ASTM D3574) pushes air through a foam sample of a specific size and thickness at a controlled pressure. The volume of air that passes through per minute is the CFM rating. Higher CFM means more airflow, which generally means a cooler sleeping experience.
CFM Rating Guide for Mattress Foam
- 0-1 CFM: Very low airflow. Traditional closed-cell foams and early-generation memory foam fall here. These foams trap heat significantly.
- 1-3 CFM: Low to moderate airflow. Standard memory foam and some polyfoams. Noticeable heat retention, especially for hot sleepers.
- 3-5 CFM: Moderate airflow. Open-cell memory foam and quality polyfoam. Most sleepers find this range comfortable for temperature.
- 5-10 CFM: Good airflow. Open-cell foams with engineered air channels. Significantly cooler than traditional foam.
- 10+ CFM: High airflow. Highly porous open-cell foams, latex, and specialty breathable foams. Closest to sleeping on a non-foam surface in terms of heat dissipation.
Why CFM Matters for Sleep
Your body generates heat all night. A mattress with low CFM acts like insulation, trapping that heat between your body and the foam. A mattress with higher CFM allows heat to dissipate through the material, keeping the sleep surface closer to ambient room temperature.
Temperature and Sleep Quality
Research by Okamoto-Mizuno and Mizuno (2012) published in the Journal of Physiological Anthropology found that thermal environment is one of the most significant factors affecting sleep quality. Elevated skin temperature delays sleep onset and reduces time spent in deep sleep stages. A mattress that allows better airflow helps maintain the slight drop in core body temperature that signals your brain it is time for deep sleep.
Open-Cell Foam: Pros and Cons
Open-cell foam has become the dominant type in modern mattresses, and for good reason. But it comes with trade-offs.
Advantages
- Better airflow: The interconnected cell structure allows air to move through the foam, dissipating body heat more effectively
- Moisture management: Open cells allow sweat vapour to migrate through the foam rather than pooling at the surface
- Softer feel: The flexible cell walls create a plush, conforming feel that many sleepers prefer
- Faster recovery: Air flowing back into compressed cells helps the foam return to shape more quickly
- Less off-gassing: Open-cell structure allows volatile organic compounds (VOCs) to dissipate faster during the break-in period
Disadvantages
- Less durable: Open cell walls are thinner and more prone to breaking down over time, which can lead to faster sagging
- Lower density options: Highly open-cell foams tend to be lower density, which means less support and shorter lifespan
- Absorbs moisture: While breathable, open cells can also absorb liquid spills more deeply than closed-cell foams
- Less firm: Not ideal for sleepers who need very firm support, as the flexible cell walls compress more easily
Closed-Cell Foam: Pros and Cons
Closed-cell foams are less common in mattress comfort layers but still play important roles in mattress construction.
Advantages
- Higher density and firmness: Trapped gas provides structural resistance, making the foam firmer and more supportive
- Greater durability: Intact cell walls are more resistant to breakdown and compression set
- Moisture resistance: Closed cells do not absorb water, making the foam more resistant to spills and humidity
- Better insulation: Useful in applications where heat retention is desirable (not sleep, but in construction and industrial uses)
Disadvantages
- Sleeps hot: Low airflow means heat builds up at the sleep surface. This is the primary complaint about traditional memory foam.
- Slower recovery: Without airflow to help the foam rebound, closed-cell foams can feel "stuck" and slow to return to shape
- Heavier: Higher density makes mattresses with significant closed-cell content heavier and harder to move
- More off-gassing: VOCs dissipate more slowly from closed-cell foam because the sealed cells trap gases longer
Where You Find Closed-Cell Foam in Mattresses
Most mattress manufacturers use closed-cell foam strategically rather than throughout the entire mattress:
- Edge support: Denser closed-cell foam around the perimeter prevents edge collapse when sitting on the side of the bed
- Base layers: Some mattresses use closed-cell foam as a foundation layer for structural support
- Transition layers: A denser layer between soft comfort foam and the coil unit can prevent you from "bottoming out"
How Foam Type Affects Sleep Temperature
This is where the science meets the showroom. Understanding foam cell structure helps explain why some mattresses sleep hot and others do not.
Temperature Comparison by Foam Type
- Traditional memory foam (closed-cell): Sleeps warmest. The dense, closed structure retains body heat. This is the "sleeping in a body-shaped oven" feel that gave memory foam a reputation for heat.
- Open-cell memory foam: Sleeps moderately cool. Engineered to allow more airflow while retaining the conforming feel of memory foam. Most mid-range and premium memory foam mattresses now use this technology.
- Gel-infused foam: Slightly cooler initially. Gel beads absorb heat at first but eventually reach thermal equilibrium and stop providing a cooling effect. Open-cell structure matters more for sustained cooling than gel infusion.
- Copper or graphite-infused foam: These materials conduct heat away from the body. Combined with open-cell structure, they provide more sustained cooling than gel alone.
- Latex foam (natural or synthetic): Naturally open-cell with pin-hole construction. Typically the highest airflow of any foam type, with CFM ratings often above 10. Our Restonic Revive Tiffany Rose/Jasmine uses Talalay Copper Latex for excellent breathability.
- Innerspring/hybrid: Coil layers naturally allow airflow around the springs. Combined with open-cell foam comfort layers, hybrid mattresses tend to sleep the coolest overall.
Ontario's Temperature Swings
Brantford gets both humid summers and dry, heated winters. Both extremes affect how your mattress feels. In summer humidity, closed-cell foam traps moisture and heat, making sleep uncomfortable even with air conditioning. In winter, heated homes with low humidity can make overly breathable foam feel cool (which some people actually prefer). The best choice for Ontario's climate is usually a moderate open-cell foam or hybrid that handles both seasons. Dorothy at our Brantford showroom can walk you through options that work year-round.
Choosing the Right Foam for Your Sleep
Now that you understand the science, here is how to apply it when shopping for a mattress.
If You Sleep Hot
Prioritize open-cell foam with higher CFM ratings. Look for:
- Latex comfort layers (highest natural airflow)
- Hybrid designs with coil cores (natural ventilation)
- Open-cell memory foam with copper or graphite infusion
- Avoid: traditional memory foam, all-foam mattresses with thick closed-cell layers
If You Sleep Cold
You may actually benefit from some heat retention. Consider:
- Traditional or transitional memory foam comfort layers
- All-foam construction (less ventilation than hybrid)
- Wool comfort layers, which naturally regulate temperature in both directions
If You Need Firm Support
Look for mattresses that use denser foam strategically:
- High-density open-cell foam in the support core
- Zoned coil systems with targeted support zones, like the 884 zoned coils in our Restonic Luxury Silk & Wool
- Closed-cell edge support for a stable perimeter
Questions to Ask at the Store
Shop This Topic at Mattress Miracle
Popular picks at Mattress Miracle:
- Restonic ComfortCare Dalton & Albany pocket-coil mattress
- Whitney two-sided bamboo mattress
- Somnia 3.0 support pillow
Or see all our mattresses in our Brantford showroom.
What to Ask About Foam
When shopping for a mattress, ask these questions about the foam construction: What type of foam is in the comfort layer (open-cell, closed-cell, latex)? What is the foam density? Is the memory foam traditional or open-cell? Does the mattress have any airflow-enhancing features in the foam layers? At Mattress Miracle, Brad and Dorothy can pull up the specifications for any mattress on the showroom floor and explain exactly what is inside.
Frequently Asked Questions
What is a good CFM rating for a mattress?
For most sleepers, a foam CFM rating of 4-5 or higher provides comfortable temperature regulation. Hot sleepers should look for foams rated 5+ CFM. Traditional memory foam often rates below 2 CFM, which is why it has a reputation for sleeping hot. Latex foam typically rates above 10 CFM, making it one of the most breathable foam options available.
Is open-cell foam better than closed-cell for sleeping?
For the comfort layer (the part closest to your body), open-cell foam generally provides a better sleeping experience because of its superior airflow and moisture management. However, closed-cell foam has a role in mattress construction for edge support and base layers where firmness and durability matter more than breathability. The best mattresses use both strategically.
Does gel-infused foam really sleep cooler?
Gel infusion provides an initial cooling sensation because gel absorbs heat faster than foam alone. However, once the gel reaches body temperature (usually within 20-30 minutes), the cooling effect diminishes. The cell structure of the foam matters more for sustained cooling. Open-cell gel foam sleeps cooler than closed-cell gel foam, meaning the cell structure is doing most of the work.
Can I test foam airflow in a mattress store?
You cannot measure CFM ratings in a store, but you can feel the difference. Lie on the mattress for 10-15 minutes and pay attention to whether heat builds up where your body contacts the surface. At Mattress Miracle in Brantford, we encourage customers to spend time testing mattresses and comparing how different foam types feel in terms of temperature and pressure relief. Ask Dorothy for a side-by-side comparison.
Do coil mattresses have better airflow than foam mattresses?
Yes. The open space between and around coils allows air to circulate naturally through the mattress core. This is one reason hybrid mattresses (coils plus foam comfort layers) tend to sleep cooler than all-foam mattresses. Our Restonic ComfortCare Queen, with 1,222 individually wrapped coils, provides both excellent airflow and targeted support.
Sources
- Okamoto-Mizuno, K., & Mizuno, K. (2012). Effects of thermal environment on sleep and circadian rhythm. Journal of Physiological Anthropology, 31(1), 14. doi.org/10.1186/1880-6805-31-14
- Krauchi, K. (2007). The thermophysiological cascade leading to sleep initiation in relation to phase of entrainment. Sleep Medicine Reviews, 11(6), 439-451. doi.org/10.1016/j.smrv.2007.07.001
- ASTM International. (2018). D3574 Standard Test Methods for Flexible Cellular Materials. ASTM Standards. astm.org/d3574-17
- Jacobson, B.H., et al. (2008). Effect of prescribed sleep surfaces on back pain and sleep quality in patients diagnosed with low back and shoulder pain. Journal of Chiropractic Medicine, 7(1), 1-8. doi.org/10.1016/j.jcme.2007.09.001
- Shin, M., et al. (2016). The effects of fabric for sleepwear and bedding on sleep at ambient temperatures of 17°C and 22°C. Nature and Science of Sleep, 8, 121-131. doi.org/10.2147/NSS.S100271
Visit Our Brantford Showroom
We are located at 441½ West Street in downtown Brantford. Free parking available. Our team does not work on commission, so you get honest advice based on your needs.
Mattress Miracle , 441½ West Street, Brantford, ON · (519) 770-0001
Hours: Monday–Wednesday 10am–6pm, Thursday–Friday 10am–7pm, Saturday 10am–5pm, Sunday 12pm–4pm.