I was asked a question the other day, what mat and bag do you choose for different seasons?
The quick answer is to say get a warmer bag and a better mat for winter. But what if you don’t want multiple bits of kit for different seasons? Let’s face facts, it can become very expensive to buy all the gear multiple times just to accommodate the fluctuating temperatures we experience in the UK, and the extra storage required for something that’s used only for part of the year.
So here’s my take on this perennial issue.
First and foremost you will lose more body heat to the ground than to the atmosphere. This is why everyone will tell you that an appropriate mat is incredibly important. So what mat do you choose?
There are many variations to choose from but any mat will have to meet two main criteria. Firstly, it must insulate you from the ground, even in summer you can lose huge amounts of body heat this way, and for me is the most important aspect. Secondly it must also be comfortable, a decent night’s sleep is incredibly important if you’re staying out, a good night’s sleep makes for a much better day and overall trip.
These are the main types of mat available and their characteristics.
Closed cell foam. This is the perennial favourite used for many many years and was pretty much the only option available for a long time outside of specialist equipment. These are usually very thin and uncomfortable due to the lack of any real support. However, closed cell foam is probably the best insulator out there, and in fact a 5cm thick version is used in polar regions as the go to standard because of that fact. They are very light, but bulky, and therefore usually carried on the outside of your pack. Quite often you’ll see them with a silver layer on one side to reflect any body heat adding to their efficiency. A very inexpensive option.
Inflatable mats. There has been an explosion in the variety available for this type of mat in recent years. From the very cheap, to the incredibly overpriced. Essentially they fall into two categories, insulated and non insulated. The insulated ones will have an r number associated with it, and the higher the number the better the insulation. A spring/autumn rating is around 3 to 5, and a winter rating is around 5 to 8. Non insulated mats are really only any good for summer as the separation between you and the ground is usually enough to keep you warm at that time of year, but definitely not during the colder months. Inflatable mats are usually lightweight at anything between 500 to 950gms and pack down quite small. These are by far and away the most comfortable of all the mats available.
Self inflating mats. These have been around for quite a while, but we’re very much on the expensive side until good inflatable mats became available. They consist of a memory foam core that expands when the valve is opened and air is allowed into it. Once inflated the valve is closed. Usually you can give them a little extra air with one or two breaths just for that extra little bit of comfort. However, despite providing reasonable comfort they are still not the most comfortable of options as they are usually still quite thin, around 5cm is considered thick. The big upside is that they provide excellent insulation being a much thicker foam than the closed cell variety. The drawback is that they are very heavy and very bulky.
On to bags.
There are two main types, synthetic and down.
Down are lighter, pack smaller, and give greater insulation weight for weight. The downsides (no pun intended) are that you have to be very careful when choosing a down bag, as quality and fill vary enormously. Not all down bags are created equal, plus they are usually more expensive than synthetic bags. Also, the moment down gets even damp it loses it’s insulating qualities, which as you can imagine could be catastrophic. However, most decent bags will use a hydrophobic coating.
Synthetic bags don’t lose their insulation when damp, but they are usually heavier and bulkier than down. Also, they tend to be far less expensive than down for the equivalent rating.
The important thing to bear in mind with bags are the two ratings given. One is the comfort rating, the other is the extreme rating. I think it’s fairly self explanatory but here’s the kicker. Sleeping bag manufacturers lie!!! They all do, even the reputable ones. As a general rule of thumb take off at least 5c from it’s rating, so if the bag states that it has a comfort rating of -2 it probably means that by the time it gets to freezing point you’ll already be feeling the cold. My bag has a comfort rating of -10c but I wouldn’t trust it below -5, and it comes from a good and reputable brand.
A sleeping bag liner can add a good 5c of warmth if you want that bit extra without forking out for another bag, as can layering your clothing for sleep. In fact there’s a lot you can do to stay warm with whatever kit you have, but that’s a subject for another post.
To go back to the original question, what do I choose to use for different seasons? The answer is simple, for me I use the same in all seasons, I just adapt or use my kit differently according to conditions. For example, in summer I open up my bag and use it as a quilt to stop over heating, whilst not sleeping in very much at all. In winter it’s fully closed, I’m wearing thermals and a hat (and maybe even a fleece), and possibly using a bag liner as well. These days I use the same r5.8 inflatable mat all year round and bolster that with a thin closed cell foam mat with a reflective face if needed. For me it’s all about adapting my kit, not buying more.
But if you want a complete selection of kit to choose from then that’s fine too, because let’s face it, it’s all about choice and personal preference.