Sealy Harlow Ortho Plus Single Mattress
The Sealy Harlow Ortho Plus is a firm orthopaedic mattress, handcrafted in the UK and sold exclusively through Mattress Online.
- Firm feel for back & front sleepers
- Fibre top cushions hips & shoulders
- 100% recyclable at end of life
£314
Get the lowest price we've found
Save with the previous model
Some retailers still sell the earlier version of this mattress for less than the current model's best price.
Sealy Harlow Ortho Plus Mattress
More available sizes
Mattress details
Mattress
Sealy Harlow Ortho Plus Mattress
Size
Firmness
Firm
Construction
Orthopaedic
Open Coil Spring
Depth (cm)
26
Layers
2
Layer Details
Comfort Layer
Soft white fibre fillings sit at the surface to cushion the hardest parts of the body, which means your hips and shoulders get a little give before reaching the firmer support below. It's a traditional filling with a slightly springier feel than foam.
Support System
PostureTech Core Support Springs use unique shapes and varied tension across the mattress, which means fuller support where your body presses hardest and pressure relief where it doesn't. This is the layer doing most of the orthopaedic work.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
- Fits where other sizes won't: At 90cm wide, the UK single needs just 2.1m x 2.8m of floor space by our guidance, so it works in box rooms and under loft slopes.
- Firm support for growing sleepers: The PostureTech Core Support Springs give a firm, even surface, which suits teenagers who sleep on their back or front and need proper support rather than sink.
- A sensible guest room choice: A firm feel is a safe bet for visitors of varied builds, and a single leaves room for a desk in a spare room that doubles as an office.
- No flipping, even in awkward spots: It's single-sided, so once it's up a bunk ladder or into a cabin bed frame, it stays put and only needs occasional rotating.
- Cheap, easy bedding: Standard single sheets and a 135 x 200cm single duvet fit, and they're the most widely stocked bedding of any UK size.
This size suits you if...
You're buying for a child or teenager who needs firm, supportive sleep as they grow, you're kitting out a spare room or student flat where the frame is already a single, or you're a solo adult in a compact bedroom where a UK single's 90cm width leaves floor space free for a wardrobe and desk. It also suits guest rooms set up with two beds rather than one.
Consider another size if...
You're an adult who shares the bed, or a restless solo sleeper who wants more room to spread out. We'd recommend the UK small double instead: it's 30cm wider, the same length, and we suggest at least 2.4m x 2.8m of floor space for it.
Similar Mattresses in This Price Range
Did you know? On Mattress Unboxed we have over 1,000 different mattresses to suit all types of sleepers. View all mattresses.
FAQ's
Will the Sealy Harlow Ortho Plus UK single fit a bunk bed?
The footprint is standard at 90 x 190cm, so it matches UK bunk, cabin and mid-sleeper frames for width and length. The thing to check is depth: at 26cm this is a reasonably deep mattress, and raised frames often specify a maximum so the safety rail still sits high enough. Check your frame's guidance before ordering.
Is the Sealy Harlow Ortho Plus single suitable for a child?
For older children and teenagers who sleep on their back or front, the firm orthopaedic support is a good match for a growing body. Lightweight side sleepers, which many children are, may find it a little unyielding at the shoulder and hip, so consider how your child sleeps before choosing a firm mattress.
How much room does a UK single mattress need?
We suggest allowing at least 2.1m x 2.8m of floor space, which gives you walking room alongside the bed. That makes the UK single a practical fit for box rooms, loft conversions with a narrow usable footprint, and children's rooms where the bed competes with toy storage, a wardrobe and a desk.
Is a single Sealy Harlow Ortho Plus good for a spare room?
Yes, with a caveat. The firm feel suits occasional guests of most builds, and a single leaves space for a desk if the room doubles as an office. Some owner reviews mention weaker edge support, though that matters less on a bed used a few nights a month than on one slept in nightly.
Can two Sealy Harlow Ortho Plus singles work for a guest room?
Two UK singles is a flexible guest room setup: separate beds for friends or siblings, and each mattress is 90cm wide and 190cm long, so measure for both plus a walkway between them. Because the feel is firm across the whole surface, both guests get consistent support whichever bed they take.