Dormeo Octasmart Plus reviewed

The Dormeo Octasmart Plus is a 17cm all-foam mattress with a medium feel, built from a thin layer of memory foam over 9cm of Octaspring foam springs arranged in three support zones. It is the cheapest mattress in Dormeo’s UK range with a full 9cm Octaspring layer, and it costs £499 in a UK double at the time of writing (September 2026). Dormeo’s product page shows an average of 4.3 out of 5 from 1,047 customer reviews.

What is inside the Octasmart Plus

The Octasmart Plus specification on dormeo.co.uk lists three layers under the cover. Dormeo does not print the memory foam depth for this model, but its Octasmart Deluxe page describes the Deluxe’s 4cm layer as twice the memory foam of the Plus, which puts the Plus at 2cm.

Octasprings are hollow, honeycomb-shaped foam cylinders rather than a solid block. Dormeo says that structure makes the mattress eight times more breathable than traditional foam and can lower the temperature of your sleeping environment by up to 3°C; those are the manufacturer’s own figures. Heat is worth designing against, because a 2012 review in the Journal of Physiological Anthropology (Okamoto-Mizuno and Mizuno) found that heat exposure increases wakefulness and reduces deep and REM sleep, and that normal sleep goes with a bed climate of around 32 to 34°C.

Feel and who it suits

Dormeo rates the Plus as medium, which we score 5 out of 10. Firmer Octasprings sit under the hips and softer ones under the shoulders, so side sleepers get some give at the shoulder without the hips dropping. Medium is also where the evidence on back pain points. In a randomised trial of 313 adults published in The Lancet (Kovacs et al., 2003), people with chronic low-back pain improved more on medium-firm mattresses than on firm ones over 90 days.

Depth is the limit. With 2cm of memory foam and 17cm in total, heavier sleepers reach the spring layer quickly, and Dormeo rates the mattress for up to 22 stone per side. The small double (120 x 190cm) is a useful extra that most of the Octasmart range does not offer.

Prices by size

Trial, warranty and care

Dormeo’s 200-night trial starts on the day of delivery, the mattress has to be unpacked within 30 days, and because the Plus contains Octaspring technology Dormeo collects a return free of charge. The Octasmart warranty covers the core for 18 years and the cover for one year, but only the first five years are full cover. After that you pay a rising share of a replacement, half the price after eight years. Dormeo also asks for slat gaps of no more than 7.5cm and recommends turning the mattress head to toe weekly for the first four weeks, then every four weeks. The trial FAQ on the product page also requires the mattress to be used with a mattress protector.