The cover on the Glacier 4000 is cold under your palm, like the underside of a pillow on a summer night. That's the whole promise of TheraPur, Dreams' own range of cooling mattresses, and if you wake up hot, that's what brought you here. Of the five ActiGel mattresses numbered in round thousands from the Polar 2000 up to the Alaska 6000, the Glacier sits in the middle and is the Medium, made for people who want gel cooling without a firm bed. You get a quilted pillow top over gel foam, a shallow sheet of micro springs and full-height pocket springs, 28cm deep. I spent proper time on it in a Dreams store in March 2026, and there's a lot about it I like.
On my side I could feel the gel working under my shoulder and hip, with enough give to take the sharpness out of both while my waist stayed supported. It read as a true medium, where plenty of beds sold as medium lie firm. You get a gentle cushion first and then a steady push from the springs, so you stay up on the springs and never drop down into the foam.
That cushion is the pillow top. The gel under it cushions and then lets go, closer to a springy modern foam than the slow melt of old memory foam. On my back it was comfortable, though if you want a level lift through your lower back you should go a shade firmer. A quick roll onto my front told me I wouldn't choose it for anyone who sleeps face down most nights.
Side sleepers of around average weight who run hot are the people it's made for, along with anyone who swaps between side and back through the night and wants a medium bed that's cool to the touch. Walk away if you sleep on your front, if your back wants firm support, or if you'd like a mattress you can turn over when it starts to wear, because this one has a single face with the top stitched to it.
Cold the moment you lie down, and owners back the cooling
The cooling is the best thing about the Glacier, and owners back it hard. Heatwaves come up again and again in their reviews, and one sums up getting into bed as "such a coolness". That was my first impression in the shop too. I'm usually a hard sell on cooling covers, since a fabric can only feel cold until it has warmed through, but this graphite-knit one is among the best I've touched at the price: cold on contact, and never slick or plasticky, with none of the raincoat feel some cooling fabrics have.
Beneath the knit are a fibre layer and two sheets of ActiGel, the gel foam the range is named after, with 4cm of it zoned to firm up in some places and give in others. Good as the cover is, the gel is the half I trust over a whole night. Gel foam is a mild help and never a miracle, but it helps, and there's no memory foam in this bed to hold heat around you. My evenings go warm shower, cool room, then bed, and a surface that's cold under your hand fits straight into that.
Dreams says the cover will end overheating for good. One owner who runs very warm found it less cooling than they'd hoped, so keep the bedroom cool and the duvet tog down as well.
There's one snag, and it's in Dreams' own terms. Its 100-Night Comfort Guarantee only lets you swap the mattress if a protector has been on it from the first night, which puts a layer of fabric between you and the cover you're paying for. One owner wonders how good the gel is for exactly that reason. I'm not a protector fan at the best of times, and on this bed it's like a cheap case on an expensive phone. Use one, since the swap depends on it, and choose a light cotton protector over anything padded or rubber-backed.
The pillow top is lovely on night one, and it's why I'd look elsewhere
Give the top its due. It's a separate quilted panel stitched on above the mattress, and it's what makes the first few centimetres soft and cushioned before the gel and springs take over. Owners love it for that, one saying "the extra pillow top just makes it so super comfortable", and under a side sleeper's shoulder on the first night it's a kind thing to lie on.
To my mind, though, pillow tops cause more trouble than they solve. The padding in a top is the softest part of any mattress and the first to pack down, and once it dents where you lie, you sleep in the dent. You can't flip this one to start again on a fresh face, because it's single-sided. TheraPur owners report a lot of dipping, and one owner of this model describes the middle sinking within the first couple of weeks.
A dip in the first weeks worries me more than any other complaint a bed can draw, and a soft top on a one-faced mattress is the likeliest place for one. Dreams guarantees the Glacier for ten years, but its terms of sale also count natural settling out of what it will put right, and a hollow pressed into a soft top is easy to call settling. I'd want a long trial and free collection before buying any TheraPur. Dreams' exchange is a swap for another mattress, after the first month, once, with a collection charge.
So my verdict is clear, and a fond one. The cooling is the part worth paying for, and you can have the same graphite cover and the same gel idea on a TheraPur with a flat top: the TheraPur ActiGel Polar 2000 if you came for a medium, the TheraPur ActiGel Arctic 3000 if you like a hard bed. Neither has a top to dent.
Next to the Arctic 3000, the Glacier adds a softer grade and the top
One rung down, the Arctic 3000 is built from the same seven layers, named the same way: the graphite cover, a fibre layer, two gel foams, micro springs, pocket springs and a foam border round the edge. Move up to the Glacier and you get a centimetre more gel, 2cm more depth, 1,448 more springs in a double, a grade three steps softer on Dreams' seven-step scale, and the pillow top. No new material goes in beyond the top. The Arctic is Firm to Very Firm, so it's only the swap for somebody who likes hard.
For everyone else the swap is the Polar 2000, two rungs down: Medium Firm, one step firmer than the Glacier, with a plain quilted face, 26cm deep and no foam border. Go the other way and the TheraPur ActiGel Tundra 5000 and TheraPur ActiGel Alaska 6000 above this one wear pillow tops too, so climbing the range never gets you away from the top.
The 4000 is a tier name, and the spring count grows with the size
A double carries 4,034 pocket springs, close to the number on the label, but the label is a tier name: the Arctic 3000 below it has 2,586 in a double and the Tundra 5000 above it 4,314. A single has 2,699, a king 4,752 and a super king 5,660: the same density of springs spread over more bed, so the count tells you the size and very little about the build. Part of every count is one shallow sheet of micro springs laid over the full-height pocket springs. Micro springs mostly pad a number, to my mind, and above about 1,500 in a king the extra ones are rarely what holds you up.
The 4000 on the ticket does far more selling than anything I could feel under my hip in the shop. The full-height springs underneath carry your weight, and the comfort layers above them decide how the bed feels, so if a bigger number is tempting you up the range, compare the tops and the foam instead.
Owners can't agree whether it's soft or hard
Owners split on the feel in both directions. Some found it much softer than they expected, others harder, and one found the delivered bed so unlike the one in the shop that they swapped it. When owners keep calling a bed firmer or softer than its label, I believe them. Here they pull both ways, which tells me the Medium label is doing less work than it should. A soft top over a firmer spring core is the classic way to get that split, because how far you press through the top decides which half of the bed you feel.
Read it by weight first, then position. Around average weight on your side, you'll get the medium I lay on. Lighter or heavier than that, the same mattress can tip either way, so give it a proper ten minutes in the shop lying the way you sleep. Dreams sells it online as well, and if the one you get turns out wrong, the exchange is your way out. One owner came to the Glacier that way, after a tufted mattress didn't suit, and found the swap easy.
A steady edge and a quiet surface for two
Dreams runs a foam border round the springs, and when I sat on the edge and then lay out near it, it felt confident. It's no rigid hotel edge, but there was no roll towards the floor, so a double keeps most of its width for two people. I pressed down hard where a torso would lie and the movement didn't run across the surface. Pocket springs under gel foam keep a partner's turning on their own side, which suits a light sleeper sharing with a fidget.
28cm deep, delivered flat, and a 38kg double to rotate
At 28cm (11 inches) it sits inside what a standard fitted sheet is cut for, but near the top of it, and two owners say to plan for deeper fitted sheets. Believe them. It comes flat and full size in one piece, so measure the stairs and the turn on the landing before you order.
A double weighs 38kg, about six stone, and Dreams wants it turned end to end weekly through its first three months, then monthly from there on. With one face, rotation is the only way to spread the wear, so make it a two-person job and keep it up. Two faces share the wear better than one, and the trade's habit of building one-sided beds mostly saves the maker money. Owners differ on how heavy it feels to shift. The standard version isn't made for an adjustable base, and Dreams sells a separate Sleepmotion version for its own adjustable beds, for a little more.
What to buy instead
Buy the TheraPur ActiGel Polar 2000 if you came for the Glacier's cooling and a medium-ish feel. It's one grade firmer, Medium Firm, which is where I'd start most people anyway, and it carries the same graphite-knit cover and zoned gel with a flat quilted top, so there's nothing on it to pack down. Its guarantee is one year where the Glacier's is ten, so go in knowing that. I'd still take a flat top on one year over a pillow top on ten.
Buy the TheraPur ActiGel Arctic 3000 if you're a heavier back or front sleeper who wants the gel feel firm. It's the Glacier without the top: the same layers by name and the same ten-year guarantee, 2cm slimmer at 26cm, graded Firm to Very Firm.
Light side sleepers should know the Polar 2000 will feel firm under a slim shoulder. For them, Dreams has the Dream Team Ashbourne 2000 Pocket Wool Mattress: a Soft grade, British wool on both faces of a pocket-spring unit, and two sides to turn between. Wool keeps a bed cool with no gel involved.
