Quick Answer: Memory foam retains significantly more heat than spring mattresses. Innerspring mattresses have open air channels through the coil system, allowing airflow. Dense foam traps heat. Ontario's cold winters add a twist: some cold sleepers find warming memory foam comfortable from October to April. If you sleep hot year-round, spring or latex is likely the better choice.
Table of Contents — Reading Time: 8 minutes
- Why Sleep Temperature Matters
- How Memory Foam Traps Heat
- How Spring Mattresses Breathe
- The Ontario Climate Consideration
- Hybrids: The Temperature Compromise
- Gel-Infused Foam: Partial Solution
- How Bedding and Covers Affect Temperature
- Who Sleeps Hot vs Cold
- Frequently Asked Questions
- Sources
- Visit Our Brantford Showroom
Why Sleep Temperature Matters
Your core body temperature drops by roughly 1-2 degrees Celsius as you fall asleep. This temperature drop is part of the signal your body uses to initiate sleep. A mattress that retains your body heat and keeps you warmer than your body wants to be can delay sleep onset and fragment the sleep you do get.
For people who naturally sleep warm -- who kick off covers, wake up sweating, or find their partner's body heat uncomfortable -- mattress material choice can make a real difference in sleep quality.
This comparison has particular relevance in Ontario, where the question is not just "does this mattress sleep cool?" but "does it sleep cool in July AND warm enough in January?" That seasonal dimension is worth thinking through before you buy.
How Memory Foam Traps Heat
Memory foam is dense. That density is what gives it the contouring and pressure-relief properties people love, but it also means there is very little space for air to move. When you lie on memory foam, your body heat warms the foam surface directly underneath you, and that heat has nowhere to go. It builds up over the course of a night.
The heat-trapping effect is more pronounced with:
- Higher-density foam (5+ lb per cubic foot retains more heat than 3 lb foam)
- Thicker foam layers (4-inch foam layer holds more heat than 2-inch)
- Slow-recovery foam (traditional memory foam responds slowly and holds heat longer than faster-recovery formulations)
Why foam warms up slowly, then stays warm. Traditional memory foam is viscoelastic -- temperature-sensitive. It softens when warm, which is part of how it contours to your body. This temperature-reactivity is a feature for pressure relief but a drawback for heat management. The foam effectively acts as a heat sink, absorbing and holding warmth from your body throughout the night.
Many people who try a memory foam mattress in a showroom on a cool autumn day have a different experience in July. The ambient temperature of your bedroom directly affects how much additional heat the foam retains.
How Spring Mattresses Breathe
An innerspring mattress has a fundamentally different structure. The coil system -- whether Bonnell, continuous, or pocket coils -- creates open space within the mattress. Air can move through that space, carrying heat away from your sleep surface as you shift and move during the night.
The comfort layers on top of the coils still matter. A spring mattress with a thick, dense memory foam comfort layer will sleep warmer than a spring mattress with a fibre or cotton comfort layer. But even with foam comfort layers, the coil system below allows convective airflow that all-foam mattresses cannot match.
Pocket coils breathe better than Bonnell. Individually wrapped (pocket) coils are each encased in fabric, which slightly reduces airflow compared to open Bonnell coils. But both spring types allow significantly more air movement than any all-foam mattress. The bigger variable is the comfort layer material above the coils.
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The Ontario Climate Consideration
Most mattress temperature comparisons are written for a generic audience. Here in Ontario, we have seasons that genuinely affect this calculation.
From November through March, many bedrooms in Brantford drop to 16-18 degrees Celsius overnight, particularly in older homes or rooms far from the furnace. In a cold bedroom, a mattress that warms up and holds heat is not a liability -- for some sleepers, it is a genuine comfort advantage. People who sleep cold, or who struggle with cold feet in winter, sometimes find that memory foam's heat retention keeps them more comfortable on a cold night.
From June through September, that same property reverses. A bedroom at 22-26 degrees Celsius with humidity from Lake Erie weather systems is a very different environment. The memory foam that felt pleasant in January now runs hot, contributing to restless sleep.
The seasonal split question. When customers mention temperature as a concern, Dorothy at Mattress Miracle asks two things: what is your bedroom temperature year-round, and do you share the bed with a partner who runs at a different temperature? For couples where one person sleeps hot and the other cold, the mattress material alone cannot solve the problem -- bedding and room temperature management matter equally.
If your bedroom is climate-controlled and stays roughly consistent year-round, the conventional advice holds: memory foam sleeps warmer, spring sleeps cooler. If your bedroom temperature swings with the seasons, your answer depends on which extreme bothers you more.
Hybrids: The Temperature Compromise
Hybrid mattresses, which combine a pocket coil base with foam comfort layers, offer a middle-ground temperature profile. The coil system provides airflow that all-foam mattresses lack, while the foam comfort layer offers pressure relief. The result is a sleep surface that typically runs cooler than all-foam but not as cool as a spring mattress with non-foam comfort layers.
Hybrids are often recommended for people who want memory foam's comfort but find pure foam too warm. The Restonic ComfortCare at Mattress Miracle, with 1,222 individually wrapped coils and premium comfort layers, exemplifies this hybrid approach -- the coil core allows airflow that a stacked-foam construction cannot provide.
Gel-Infused Foam: Partial Solution
Gel-infused memory foam was developed specifically to address heat retention. Gel beads or a gel layer are incorporated into the foam to dissipate body heat more quickly. The effect is real but limited.
Most independent testing and consumer experience suggests gel-infused foam sleeps slightly cooler than traditional memory foam in the first hour or two. After that, once the gel layer has absorbed heat, the advantage diminishes significantly. Gel foam is better than standard memory foam for temperature, but it does not close the gap with spring or latex mattresses.
Open-cell foam is a better answer than gel. Open-cell memory foam has a more porous cell structure than traditional closed-cell foam. This allows more air movement through the foam itself. Open-cell foam sacrifices some of the pressure-relief depth of traditional memory foam, but it genuinely sleeps cooler. If a foam topper or mattress is labelled open-cell, it is a more meaningful temperature upgrade than gel infusion alone.
How Bedding and Covers Affect Temperature
The mattress is only one part of your sleep temperature equation. Fitted sheet material, comforter fill, and mattress protector all contribute. A hot-sleeping person on a spring mattress with a flannel sheet and a synthetic comforter may sleep just as warm as someone on memory foam with a bamboo sheet and a down-alternative duvet.
Practical steps for temperature management:
- Breathable sheet materials: cotton percale, bamboo, and Tencel (lyocell) all outperform polyester for airflow
- Natural fill comforters: down regulates temperature better than most synthetics
- Mattress protectors: waterproof protectors with a polyurethane barrier can slightly trap heat; look for protectors with a cotton or Tencel top surface
- Bedroom temperature: keeping the room at 16-19 degrees Celsius is the most effective single intervention for hot sleepers
Who Sleeps Hot vs Cold
Certain factors consistently predict whether someone will be temperature-sensitive on a mattress:
| Likely to Sleep Hot | Likely to Sleep Cold |
|---|---|
| Higher body weight (more metabolic heat) | Lower body weight |
| Men (higher average metabolic rate) | Women (especially those with lower circulation) |
| Perimenopause / menopause (hot flashes) | Thyroid conditions (hypothyroidism) |
| Warmer bedroom environment | Cold bedroom, drafty room |
| Heavier comforters or flannel bedding | Light sleepers who prefer more covers |
If you share a bed with someone whose temperature preferences differ from yours, a split setup (different bedding on each side) or a zoned hybrid mattress can help. Some couples resolve this with separate comforters -- a Scandinavian approach that is increasingly popular in Canadian homes.
Talia's Note: When couples come in and temperature is the sticking point, we usually find that the hot sleeper's concern is the dominant one -- because overheating wakes you up, while being mildly cool is solved by an extra blanket. We tend to guide toward a spring or hybrid in those situations and let the cold sleeper add a light wool blanket on their side.
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Find Your Perfect Mattress at Mattress Miracle
We are a family-owned mattress store in Brantford, helping our community sleep better since 1987. Come try mattresses in person and get honest, no-pressure advice.
441 1/2 West Street, Brantford, Ontario
Call 519-770-0001Frequently Asked Questions
Does memory foam really sleep that much hotter than a spring mattress?
For most people, yes, especially in warmer months or climates. The dense structure of memory foam restricts airflow, causing heat to build up underneath your body. Spring mattresses have an open coil system that allows convective airflow. The difference is most noticeable for people who already tend to sleep warm or who sleep in a room that isn't well air-conditioned.
Is gel-infused foam a good solution for hot sleepers?
It helps somewhat, particularly in the first hour or two of sleep. After that, the gel layer typically reaches equilibrium with your body heat and the cooling effect diminishes. For reliably cooler sleep in a foam mattress, open-cell foam construction or a latex option is a more effective solution than gel infusion alone.
Should Ontario winters change how I think about mattress temperature?
Yes. If your bedroom drops below 18 degrees Celsius in winter, memory foam's heat retention becomes less of a problem and may feel comfortable for cold sleepers. The concern is the summer season -- if your bedroom isn't air-conditioned or runs warm in summer, the heat-trapping properties of memory foam will be most noticeable from June through September.
What is the coolest-sleeping mattress type?
Natural latex is generally the coolest-sleeping foam-like material, due to its open-cell structure and natural breathability. Innerspring mattresses with non-foam comfort layers (cotton, wool, or fibre) sleep the coolest overall. If you need a foam feel but sleep hot, a hybrid with a natural latex or open-cell foam comfort layer is your best option.
Sources
- Harding, E.C., et al. "The Temperature Dependence of Sleep." Frontiers in Neuroscience, 13:336, 2019.
- Sleep Foundation. "Best Mattress for Hot Sleepers." sleepfoundation.org, updated 2024.
- Consumer Reports. "Do Gel Mattresses Really Sleep Cooler?" consumerreports.org, 2022.
- National Sleep Foundation. "Bedroom Temperature and Sleep Quality." thensf.org, 2023.
- Okamoto-Mizuno, K., Mizuno, K. "Effects of thermal environment on sleep and circadian rhythm." Journal of Physiological Anthropology, 31(1):14, 2012.
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.
If temperature is your main concern when comparing spring and foam mattresses, come in and spend some time on each type. It is the only reliable way to know how your body responds.