TheraPur ActiGel Cool Mattress Topper reviewed

The TheraPur ActiGel Cool Mattress Topper is a 4cm layer of zoned ActiGel foam under a polyester top cover designed to wick moisture away, sold only by Dreams in four UK sizes. It is aimed at warm sleepers who want to soften a firm mattress or a sofa bed without adding the height and heat of a deep memory foam topper.

Specification

Does a cooling topper matter?

Heat is one of the better documented causes of broken sleep. A 2012 review in the Journal of Physiological Anthropology (Okamoto-Mizuno and Mizuno) concluded that, when people sleep with bedding and clothing, heat exposure increases wakefulness and cuts slow-wave and REM sleep, and that humid heat adds to the load. The NHS guide to insomnia likewise lists a room that is too hot or cold, and an uncomfortable bed, among the most common causes of insomnia.

Dreams does not publish temperature measurements for ActiGel, so the cooling case for this topper rests on two things you can check: a cover built to move moisture away from the skin, and a foam layer only 4cm thick, which leaves less material between you and the mattress than a typical deep memory foam topper. The zoning varies support along the length of the body.

Feel and who it suits

Dreams gives no firmness grade. From the construction we would place it around 5 out of 10: softer than the mattress it sits on, with none of the slow sink of thick visco foam. It suits side and back sleepers on a mattress that feels too hard, guest beds and sofa beds. If your mattress has dipped or lost support, a 4cm topper will follow the dip rather than fix it.

Allergy sufferers should know that the NHS advice on allergic rhinitis, which names house dust mites among the common triggers, includes washing bedding regularly at 60°C and above. The ActiGel Cool cover is rated for 30°C, so pair the topper with a mattress protector you can wash hotter.

Sizes and prices

Prices are from the Dreams product page at the time of writing (September 2026), with all four sizes in stock.

Dreams lists the topper as available online, with free delivery from two days after ordering. Its 100-night comfort guarantee covers mattresses only, so treat a topper purchase as covered by the normal returns policy rather than a sleep trial.