A mattress cannot cool a room. It can retain more or less heat around the body and allow moisture to escape differently. The core matters, but it never works alone.
Start with pocket-sprung hybrids such as Marisma and Shire when deeply enveloping foam feels hot. Then check sink depth, base, protector and bedding because each can change the thermal result.
Locate where heat is being held
If you sweat while uncovered, review room temperature, humidity, sleepwear and protector before blaming only the mattress. A restrictive waterproof protector or heavy duvet can dominate the result.
Contact matters too. More enveloping surfaces expose less skin to air. That does not make every memory foam hot or every spring mattress cool; the complete build decides.
What springs can add without magic
The open interior of a spring core can move air more freely than a continuous block, and quicker response may reduce a trapped feeling. Thick upper layers can preserve or erase that advantage.
Marisma and Shire both combine springs and memory foam. Compare the comfort depth you tolerate, finished height and whether two-sided care is realistic.
The thermal check I would make
Lie down for several minutes in clothing similar to home. Notice sink depth, effort to turn and warmth at the back. Touching the surface for seconds does not reproduce a night.
On Amazon check the exact variant, returns and recommended base. For Portugal, verify delivery before choosing; a visible listing does not guarantee every postcode.
Two hybrids to start the comparison

Pikolin Marisma Seaqual
A pocket-sprung hybrid with a memory-foam comfort layer, aimed at airflow and movement independence for two.
Read review →
Pikolin Shire
A double-sided hybrid for buyers who value a substantial build and will treat turning as part of routine care.
Read review →More options to compare
Choose by size, feel and available space. These options suit different needs.

KUO Dream Bio Memory 150 × 190 × 26
Memory foam with INNOGEL, a dual-sided build and medium-high firmness for buyers balancing comfort and heat management.
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Grbsy híbrido 150 × 190 × 30
Pocket springs, gel, latex and reinforced edges make this the fullest-looking option for couples seeking lower motion transfer.
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Todocama Airsoft 150 × 190 × 21
The 150 × 190 double variant: multilayer foam, medium-high firmness and an accessible buying position.
View on Amazon →