SweetNight vs Siena: Which budget cooling mattress is better for side sleepers?

The SweetNight CoolNest Mattress and the Siena Signature Mattress are two all-foam beds that deliver excellent temperature regulation for under $400 in a queen size. However, as a side sleeper, I know which cooling mattress I'd pick when choosing between the SweetNight CoolNest vs the Siena Signature.

The Siena Signature currently ranks as our favorite budget option in this year's best mattress guide, but after testing it through summer heatwaves, we now see the CoolNest as its biggest rival. While there's little doubt that both can keep us sleeping cool, which one will have side sleepers feeling comfy?

If you're a side sleeper looking for a budget memory foam mattress, this SweetNight CoolNest vs Siena Signature comparison guide will explore the two beds in terms of price, design, and comfort, so you can make an informed decision in this month's mattress sales.

SweetNight CoolNest vs Siena Signature mattress: Specs at a glance

SweetNight CoolNest vs Siena Signature mattress: Price & Trials

• With the typical discount, a queen SweetNight is usually $399.99
• The Siena is $329 in a queen size thanks to a regular sale
• Both come with a 10-year warranty, but the Siena's trial is 80 nights longer

The 12" SweetNight CoolNest and the 10" Siena Signature are both featured in our 2026 best cheap mattress guide, with each model regularly sold under $400 in a queen and both coming with good benefits.

Right now, the SweetNight CoolNest and Siena Signature are at their typical sale prices. At SweetNight, a regular discount takes a queen to $399.99 (MSRP $579.99). Prices start at $349.99 (for both a twin XL and full size) but be aware twin and Cal king are both regularly sold out.

We don't expect this sale price to drop any further this month, though in September we did see the brand throw in $100 worth of free cooling pillows in honor of the Labor Day mattress sales.

Over at Siena, a queen Signature is $329 (with a 'Total Value' of $742 ) which makes it $70 cheaper than the queen CoolNest. Believe it or not, at times the Signature mattress has been even cheaper, dropping to $244 for a queen during holiday sale events.

Will the Siena return to under $300 for a queen during this year's Black Friday mattress sales? It's anyone's guess. But what remains a constant is Siena's extras: a 180-night sleep trial, a 10-year warranty, and free shipping and returns.

SweetNight has similar benefits, only its mattress trials are slightly shorter, at 100 nights.

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SweetNight CoolNest 12" Memory Foam Mattress (queen): was $579.99 now $399.99 at Sweetnight (US)

A twin XL is now back in stock, meaning that you can get hold of a SweetNight CoolNest from $349.99. A queen is $399.99, but at the time of writing, twin and cal-king size were unavailable. Benefits include a 100-night sleep trial, 10-year warranty, and free shipping and returns.

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Siena Signature Memory Foam Mattress (queen): $329 at Siena

The Siena Signature Mattress is currently $329 (Total Value $742) for a queen, which is a good deal on a top-rated memory foam mattress — though we have seen the mattress under $300 in a queen during past sale events. As always, you can enjoy a 10-year warranty and a 180-night sleep trial.

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SweetNight CoolNest vs Siena Signature mattress: Design & Materials

• Both have a fiberglass-free memory foam design
• SweetNight is a 12" specialist cooling bed with 6 layers
• Siena is a 10" bed with just 2 internal layers of foam

Like the beds you'll find in our best memory foam mattress guide, the SweetNight and Siena are fiberglass-free, all-foam mattresses, but they have very different builds and materials.

First of all, the SweetNight is a dedicated cooling model, whereas the Siena is a conventional memory foam mattress that just so happens to have a good deal of temperature control.

This distinction comes down to the cooling tech that the SweetNight boasts: PCM(Phase Change Material)-infused foam, cooling gel-infused memory foam and a nylon cooling cover that contains 20,000 air channels for increased ventilation. (PCMs in mattresses have been proven to improve human heat dissipation up to 25.6% compared to conventional mattresses)

The Siena's main form of cooling, meanwhile, is a lightweight, breathable cover. However, a breathable cover is pretty much an industry standard, and hardly makes the bed a cooling mattress.

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At 12" tall, the SweetNight features six internal layers of foam under the cover, including the gel-infused and PCM-infused foam layers mentioned above, comfort foam, responsive foam, a high-density foam layer, and a water-resistant, reinforced layer of base foam.

The Siena keeps its 10" build simple with just two internal foam layers under the top cover: a memory foam comfort layer followed by a stability foam support layer below. There's also a durable bottom cover.

SweetNight CoolNest vs Siena Signature mattress: Comfort & Support

• The Siena is much firmer than the medium-firm CoolNest
• The CoolNest is best for side and back sleepers
• The Siena is too firm for side sleepers, but great for front sleeping

I was the lead tester on the SweetNight CoolNest Memory Foam mattress review, meaning I trialled the CoolNest in a lab for objective results and slept on it at home for subjective analysis.

After extensive testing, I can confidently say that the CoolNest has a medium-firm feel that's ideal for side and back sleepers like me. It provided enough comfort along pressure points like the shoulders and hips when side sleeping, but also provided enough support for my lower back when back sleeping, too.

In our pressure relief tests, the SweetNight outshined the Siena in terms of comfort, with its memory foam sinking deeper in the shoulder and hip regions of the mattress's surface.

By comparison, the Siena Memory Foam displayed much less "give" in the shoulder and hip areas (and our Siena Signature mattress review lead tester noted that her "shoulder would prefer something softer" for side sleeping in the long term.) This shows that's it's generally way too firm for side sleeping.

However, the firm, responsive support meant our lead tester described the Siena as a "dream for back and stomach sleepers."

So, while it's too firm for most side sleepers, it's one of the best mattresses for stomach sleepers — and back sleepers who prefer a firmer mattress will enjoy the sturdy support, too.

Side sleepers, meanwhile, should choose the SweetNight CoolNest, as should back sleepers who need lumbar support but prefer a softer mattress. Like the best mattresses for side sleepers, it provides a balance of cushioning comfort and medium-firm support.

SweetNight CoolNest vs Siena Signature mattress: Temperature Control

• The CoolNest is a specialist cooling bed infused with PCM
• The Siena is breathable, but isn't a cooling model per se
• Both performed well in our thermal regulation tests

As mentioned, the SweetNight CoolNest is a dedicated cooling model, meaning that temperature regulation is at the forefront of its design.

However, if you take a look in our best cooling mattress guide, you'll find plenty of conventional mattresses that aren't cooling per se, but offer great temperature control (and that includes the Siena Signature).

We test temperature regulation in two ways: the first is objectively in a lab, using a thermal imaging camera, and the second is sleeping on the mattress at-home and reporting how the sleep temperature subjectively felt.

Before I began sleeping on the SweetNight at home, I unboxed it in our sleep lab. Once it expanded and was ready for testing, we felt the SweetNight's cover. My fellow testers and I couldn't believe how cool-to-the-touch it was.

Then, I slept on the SweetNight in the height of summer, plagued by heatwaves, without the aid of AC. Pairing the SweetNight with light bedding, not once did I experience night sweats or 3 a.m. wake ups from overheating.

Meanwhile, fellow mattress tester Ruth Jones slept on the Siena Signature at home. She said that, while she tends to overheat on memory foam mattresses, she "remained a comfortable temperature all night on the Siena."

In our objective thermal imaging tests, both the Siena and the SweetNight performed well. The SweetNight initially shed body heat at a much faster rate, but the Siena absorbed less heat.

From this, we think both are good choices if you want a cooler mattress on a budget. The Siena might perform slightly stronger overall, but it's the SweetNight that offers an immediate dose of icy comfort when climbing into bed.

SweetNight CoolNest vs Siena Signature mattress: Which should you buy?

Buy the SweetNight CoolNest mattress if...

✅ You want a specialist cooling tech: While the Siena is breathable and is great at dissipating body heat, the SweetNight impressed us with it's dedicated cooling tech. The icy cover delivers an immediate hit of cool when climbing into bed.

✅ You're a side sleeper: The SweetNight CoolNest has a medium-firm feel that provides body-contouring comfort along the shoulders and hips when side sleeping.

✅ You prefer a softer memory foam feel: If you're a back sleeper and torn between the Siena and the SweetNight, both are supportive but the SweetNight is a better choice if you prefer something softer.

Buy the Siena Signature mattress if...

✅ You're a back or stomach sleeper: The Siena Signature has a firm feel, which is great for supporting back and stomach sleepers.

✅ You want the cheaper option: A queen is over $70 cheaper than the SweetNight in a queen, plus you get a longer sleep trial.

✅ You want a twin, Cal king, or split king size: The SweetNight is consistently unavailable in twin and Cal King, so look to the Siena if you want these sizes (plus a split king).

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