Klymit Inertia O Zone sleeping pad review

I purchased the Klymit Inertia O Zone sleeping pad to use on top of a Therm-a-rest Z-Lite Sol Land’s End to John O’Groats walk in 2019. On this walk I used a small Thermarest Neoair XLite on top of a simple 8mm thick closed cell foam mat acting as a ground sheet. It protected the air mat from punctures, added to the overall sleep system’s insulation value and was quick to set up.

I decided to try the Klymit sleeping pad after I got a puncture in my Thermarest Neoair. Stupidly I used it without the closed cell foam mat whilst on the Isle of Wight coastal path walk. I was also a bit tired of chasing my pillow around during the night, and I liked the fact that the Klymit pad came with an integral pillow.

This review will be updated as I use and learn more about the mat. (Last updated January 2020)

Initial review: summer use

In this initial review, I tried the mat on its own. I slept on it for two nights, with the lowest temperature of around 12 degs C (55 F). I’ve updated the review further down, when I used the mat in the winter.

The Klymit Inertia O Zone sleeping pad is made with 75D fabric on the bottom and 30D on top, instead of the 30D all round the Neoair Xlite. So on future long distance walks, hopefully there will be less chance of a puncture. If I do get one, though, I’m still going to get a reasonably comfortable night’s sleep on the thicker fabric.

The pad is slightly heavier than the Neoair. I think it is worth the extra weight though for the additional comfort and because you don’t need to carry a separate pillow. The attached pillow is really nice to have; no more losing the pillow in the middle of the night!

The pillow stayed where I wanted it. It was easy to put things under it when I wanted it a little higher. You can feel the cross in the pillow, but it didn’t seem to be a problem and possibly centralised my head better.

Having holes in the rest of the mat makes it easy and quick to inflate. On long distance hikes and when I’m tired after a long day, the amount of effort the mat takes to blow up can make a big difference to my mood. It can sometimes feel like a real chore, blowing it up night after night. I definitely noticed this on my LEJOG walk.

Sleep comfort

You can inflate the mat hard, but when you sit on it, you feel like you’re on the ground. I prefer to inflate it less fully. It’s only 46mm thick, so I’m not sure if it will keep me particularly warm (this initial test was held on a relatively warm night). In comparison, the Neoair XLite is 63mm thick.

I found that when laying down, my body weight spread across the mat. This made it more solid, lifting my body off the ground more. It was also wider, meaning my arms were on the mat rather than hanging off the sides, on the ground. The holes in the mat are noticeable and they feel a little odd.

However, in saying all that, I sleep really well on it. I am extremely surprised how comfortable it is, especially as I tend to sleep on my side.

It’s a great mat, ideal for summer use or, as I intend to use it, doubled up with another mat in colder weather.

Update January 2020: winter use

I’ve recently been on two winter wild camping trips using the Klymit Inertia O Zone sleeping pad with the closed cell foam mat and the Therm-a-rest Z-Lite Sol. The temperature was below freezing every night, down to around -2C.

I found that when the basic closed cell foam mat was under the Klymit pad I was not really warm enough, especially when I was laying on my side. My hip was cold enough that it would wake me up in the night.

However, with the Thermarest Z-Lite Sol under the Klymit pad this was not an issue. I didn’t feel the cold coming up from the ground and felt comfortable. Both mats together have a similar R value as a Thermarest Neoair XLite but not as warm as a Thermarest Neoair Xtherm. I would probably use this on shorter trips where getting a puncture would be less of an issue and less weight or bulk in the rucksack was more important.