Why some people sleep hot#

Body temperature naturally drops during sleep as part of the circadian rhythm. For some people, this regulation is less efficient — they generate more heat or dissipate it less effectively, leading to night sweats and disrupted sleep. Your mattress significantly affects this: some materials trap heat, while others actively dissipate it.

In the UK, where summer temperatures have become increasingly warm and many homes lack air conditioning, sleeping temperature has become a more significant issue than in previous decades.

How different mattress materials affect temperature#

  • Traditional memory foam: The worst performer for hot sleepers. Memory foam has a closed-cell structure that traps heat and retains body warmth. If you sleep hot, traditional all-foam mattresses should be avoided.
  • Gel foam: Better than standard memory foam, but the cooling effect is limited. Gel absorbs heat initially but reaches saturation quickly. Don't rely on gel foam alone to solve a significant sleeping-hot problem.
  • Hybrid (springs + foam): The best mainstream choice for hot sleepers. The pocket spring base creates air channels that allow heat to dissipate naturally. The foam comfort layer can be kept thinner than in an all-foam mattress, reducing the insulating effect.
  • Natural latex: Open-cell structure allows excellent airflow. Natural latex consistently outperforms memory foam and gel foam for temperature regulation. A strong choice for hot sleepers.
  • Wool-topped mattresses: Wool is a natural temperature regulator, absorbing moisture and releasing it as vapour. Wool-topped mattresses (common in UK premium brands) can help balance body temperature in both warm and cool conditions.

Beyond the mattress: cooling sleep setup#

A cooler mattress is only part of the solution for hot sleepers:

  • Mattress protector: Choose a bamboo or cotton protector rather than a waterproof one (waterproof protectors trap heat). Tencel/lyocell fabric protectors are particularly breathable.
  • Duvet: A lower tog duvet (3.5–7 tog) for summer; all-season duvets allow adjustment. Natural-fill duvets (down, wool, silk) generally regulate temperature better than synthetic fills.
  • Pillows: Cooling gel pillows or buckwheat-filled pillows sleep significantly cooler than synthetic memory foam pillows.
  • Bedroom temperature: The NHS recommends a bedroom temperature of 16–18°C for optimal sleep. A fan or opening windows before bed can help significantly.

Top cooling mattress features to look for#

  • Pocket spring base (ensures airflow beneath the comfort layer)
  • Open-cell foam or latex comfort layer
  • Breathable, natural-fibre cover (cotton, wool, bamboo-derived)
  • Phase change material (PCM) in the cover layer — absorbs and releases heat to maintain a consistent sleep surface temperature