Review: Rab Ionosphere 5.5 Sleeping Mat

I’ve been venturing into more extreme conditions of late. Scottish winter was the gateway drug, and now I’m craving higher peaks, bigger challenges and colder temperatures. But with this new-found appetite for altitude comes a need for more technical kit. And with that, I’ve got a dilemma.

I know all to well how heavily the textile industry contributes to greenhouse gas emissions. Then there’s PFAS, greenwashing, end-of-life solutions… it’s really tricky to justify a selfish desire to have decent kit that’ll keep me safe and comfy in the outdoors, whilst claiming to care about protecting the outdoors too. It’s an issue that Rab seem to be acutely aware of and making some really promising efforts to address – in particular, the recent launch of their Material Facts labelling initiative, which aims to eradicate the use of confusing language like eco and sustainable, and replace them with cold, hard facts and data like the percentage of recycled materials used, fluorocarbon content and country of origin of their gear. This is currently available for all new clothing and sleeping bags, with plans to develop this across their remaining gear. Rab are certainly one of the small number of brands who seem to be making honest progress, rather than false promises, and for that I’m willing to buy in.

Back to my more physical needs: I’m after a sleeping mat that’s going to keep me warm in minus temps. With alpine bivies on the cards, it needs to be relatively light and pack down small. It needs a high R value, a decent amount of durability against abrasion and because I will wake up to the sound of gnat’s fart even when sleeping in my own bedroom, it needs to be squeak, rustle and slip-free. I’m a side sleeper too, so I need a shape that accommodates that.

The Ionosphere 5.5 is the warmest mat in Rab’s range, and the price point reflects that. For those looking for a summer-shoulder season camping mat, this one would probably be overkill. If you’re looking for something for more technical mountain adventures in colder temperatures that handles rock, snow and ice with ease, the Ionosphere 5.5 is likely to provide a long-lasting return on your investment.

Size-wise, the Ionosphere 5.5 is well suited to those with limited space in their pack, and whilst I’ve heard whispers that there are lighter mats available at a similar price point, I can’t imagine that they offer the combined insulation technology and thoughtful design that this one does, and personally, I’ll gladly take a little extra weight for a better night’s sleep. To conclude: this one’s for mountaineers and alpinists who value a decent kip, and equally for those who value environmental transparency.

Value for money is always subjective – but you probably wouldn’t be here if you weren’t in the market for a mat of this kind. It feels robust enough to have a good lifespan – keep your crampons well away and I’d say that this mat will give you many, many years of warmth and comfort. Again, if you’re after something a little lighter on your pocket or perhaps don’t need such a high R value, you might consider something more like the Stratosphere 4. I will happily use the Ionosphere 5.5 for summer camping too, just with a lighter, synthetic sleeping bag, and because I’m content with its weight and pack size, I don’t feel the need to have multiple mat options.

For my needs, the Ionosphere 5.5 does a brilliant job of balancing out weight and pack size with warmth and comfort, so is worthy of its price tag.