Silentnight Impress Memory Foam Topper Review: 5cm vs 7cm

The Silentnight Impress is the only memory foam topper we found in the range, and it’s the one with the strangest price tags. Retailers show “RRPs” of £211 to £396 next to selling prices of £90 to £149, which makes every purchase feel like a rescue. So what’s it actually worth, and should you choose the 5cm or the 7cm?

We checked Silentnight’s own page and live listings at La Redoute, MFI, Costco UK and one specialist bed retailer on 28 October 2026, then looked for owner feedback and independent guidance from Which? and the Sleep Foundation. It builds on the findings in our full Silentnight topper range review, with current prices and a clearer buying rule.

Quick Verdict

• Good value as a pressure-relief layer on a firm mattress, at roughly £65 to £149 depending on depth, size and seller. Poor value if you pay anything near the quoted RRP.
• The “RRPs” on one specialist retailer run from £210.99 to £395.99, implying 57% to 69% off. Silentnight’s own page lists the 5cm from £65 (single) and £80 (double), with “Was” prices only £5 to £15 higher.
• 5cm for a gentle change, 7cm for a very hard bed. The 7cm costs about £30 more for 2cm extra depth.
• Memory foam holds more heat than hollowfibre. Hot sleepers should look at the Airmax instead.
• It can’t repair a sagging mattress. It changes the top few centimetres only.

Is the Silentnight Impress memory foam topper worth buying?

Yes, if your mattress is too firm and your complaint is pressure on hips and shoulders. It’s a genuine memory foam layer with a washable cover, a two-year guarantee and prices that are fair once you ignore the RRP. It’s the wrong buy for hot sleepers, or anyone trying to fix a dip.

Owner scores are encouraging but come from small samples. One specialist retailer shows 5.0 out of 5 from 13 reviews on the 5cm and 4.8 from 16 on the 7cm, while La Redoute’s 5cm sits at 4.3 out of 5 from 70 reviews. Those are retailer-hosted reviews, so read them as a sign of satisfaction, not a lab test. Source: Impress 7cm retailer listing · La Redoute

What exactly is the Impress topper made of?

It’s a slab of “soft and reactive” memory foam in a removable, machine-washable cover, made in the UK. Both depths are listed as hypoallergenic and vegan friendly, conform to the BS7177 fire standard and carry a 2-year manufacturer’s guarantee. Foam density isn’t published, which makes like-for-like comparison with other brands hard.

Source: Impress 5cm retailer listing · Silentnight Impress 5cm · Costco UK

Two practical notes. Neither Silentnight’s page nor the 5cm retailer listing mentions straps, while MFI’s listing describes a non-slip base, so expect to rely on a snug fitted sheet. One La Redoute reviewer of the 5cm reported it slipping about 7cm despite its retaining bands. And MFI says the foam itself is sponge-clean only; just the cover goes in the wash. Source: MFI

How inflated are the Impress RRPs?

Heavily. MattressNextDay’s listings quote RRPs between £210.99 and £395.99 against selling prices of £90 to £149, a markdown of 57% to 69%. Silentnight’s own page, meanwhile, shows “Was” prices of £70 to £115 against current prices of £65 to £105 for the 5cm. An RRP nobody charges is a label, not a price.

Prices have moved since our September research, so older figures elsewhere may no longer hold. Today the cheapest 5cm we saw at that specialist retailer is £90 (single) and the cheapest 7cm is £129 (double). Stock matters too: the single and double 5cm showed as out of stock with a mid-January restock message, and the listing’s own stock messages conflicted, so check before ordering.

Source: Silentnight · Impress 5cm retailer listing · La Redoute

Silentnight’s own page was £18 to £25 cheaper than the specialist retailer in every 5cm size we compared, so check it before paying a third party. Our guide on how to spot a genuine Silentnight discount explains why a “was” price should never be your anchor.

Should you buy the 5cm or the 7cm Impress?

Choose the 5cm for a modest change, a lighter topper and the widest choice of sizes. Choose the 7cm if your mattress is very hard or you want deeper contouring. On the retailer listings we compared, the 7cm costs £31 more in a double and £30 more in a king, a small premium for 2cm.

Per centimetre of foam, the 7cm is slightly better value: £18.43 against £19.60 for a double, and £21.29 against £23.80 for a king. But value per centimetre isn’t the point. The deeper you go, the more the topper, not the mattress, decides how the bed feels, and the more heat it holds. One retailer reviewer called the 7cm heavy to handle, though they said it stayed put without adjustment.

Check your sheet depth before ordering. A 7cm topper on a 20cm mattress needs a fitted sheet with real depth, and our Silentnight mattress size guide will confirm the dimensions you need to match.

How does memory foam feel on top of a spring mattress?

Softer on the surface, unchanged underneath. Memory foam contours to your shape and springs back slowly, which Which? notes can feel firm and spongy. On a sprung bed, the topper spreads pressure over hips and shoulders while the springs still do the supporting. It can’t lend support the mattress has lost.

Does the Impress topper sleep hot?

It can. Foam traps heat: the Sleep Foundation calls memory foam notorious for trapping body heat, and Which? says it may feel warmer than other fills. Owner feedback on the Impress is mixed. Most of the La Redoute reviews we read don’t mention temperature, but one called the 5cm very hot and stopped using it.

Which topper suits a warm sleeper instead? Probably a hollowfibre one with airflow. We saw no cooling claim on any Impress listing. If you’re on the fence, the Airmax 500, 800 and 1000 compared shows the cooler alternative, and whether its price and owner scores justify it. Source: Sleep Foundation · Which?

Impress or Airmax: which should you pick?

Pick the Impress for pressure relief, the Airmax for cheap softness and airflow. The Impress runs about £65 to £149 depending on depth, size and seller; Silentnight’s own 8cm Airmax is £41 for a king. If your mattress is too firm but you sleep warm, the cheaper Airmax is likelier to suit.

Neither fixes a mattress that has gone. Foam follows a dip as readily as hollowfibre does, so if the bed itself is the problem, our shortlist of the best Silentnight mattresses to replace it with is the buy-new route.

Questions Owners Ask

Is the Silentnight Impress topper good for back pain?

It can relieve pressure at hips and shoulders, and one retailer reviewer reported their back pain improving. It won’t correct poor support from a worn mattress, and no review here is medical evidence. See a GP for persistent pain.

Is the 7cm Impress topper too thick for a normal mattress?

Not too thick, but you need a deep fitted sheet. A 7cm layer on a mattress of average depth adds noticeable height, and the topper is described as heavy to handle. Measure your mattress and sheet depth before ordering.

Can you wash a Silentnight Impress topper?

The cover is removable and machine washable. MFI’s listing says the foam itself is sponge-clean only, so never put the foam in the machine. Follow the care label on your topper for temperature and drying.

Why do retailers show such high RRPs for the Impress topper?

We can’t see their reasoning, but the pattern is clear: quoted RRPs of £210.99 to £395.99 sit far above anything we saw charged, while Silentnight’s own page shows “Was” prices of only £70 to £115. Compare live prices, not discount percentages.

Will a memory foam topper make my Silentnight mattress sleep hotter?

Very possibly. Foam holds more heat than hollowfibre and a thicker layer holds more. We found no cooling claim on the Impress listings, so hot sleepers may prefer an Airmax or a better-ventilated mattress.

Does the Silentnight Impress topper come with a trial?

We found no sleep trial on the Impress listings, only a 2-year manufacturer’s guarantee. Silentnight’s trials apply to mattresses, not toppers. Check each retailer’s returns policy before opening the packaging.