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Windermere Weekend

5 tips for Sleeping Warm Outdoors by Ross Bowyer

Updated: Sep 28, 2020

There is a simple pleasure in making yourself comfortable outdoors. Waking up after a warm night sleep sets you up for a great day of exploring. We live in a temperate region where our weather is dominated by maritime influences, meaning we get lots of wet weather! We can also get four seasons in one day, especially in the mountains and cold weather can occur at any time of year!

Here are my top 5 tips for sleeping warm outdoors:

1. Make sure your sleeping bag is up to the job!

Designers try to provide a guide to how warm the sleeping bag will be in two ways. Firstly, a temperature range +5 to -10 for example, the lower temperature is an ‘Extreme’ temperature, as low as the bag will go before you start losing too much heat. So, look for the ‘Comfort’ rating instead. However, this is not the same for all people which is why designers have developed a Season rating. 1 season for hot weather, 2 season for Summers, 3 season for Spring and Autumn and 4 season for Winter. If in doubt get a warmer bag as you can always open it up to cool off.

2. Make sure you have enough insulation underneath you!

There is an old saying that goes, ‘one layer under is worth two layers on top’. You could have a 4 season bag suitable for Polar regions but if you sleep directly on the ground you will loose too much heat via conduction. Insulation comes in a number of forms, the simplest is a closet cell foam mat which although bulky is cheap and very effective. At the other end of the spectrum are inflatable mats that combine foam and air to create insulation. These are very comfortable and provide excellent insulation, but are prone to leaks and can be expensive. Remember, the colder the temperature the more insulation you need under you. When I am on expedition in Northern Canada in the Winter, I sleep on a freshly laid bed of spruce boughs as well as a closed cell mat AND a inflatable mat!

3. Do not wear too many clothes in your sleeping bag!

If you think you’re going to be cold, it seems like a sensible thing to do, doesn’t it? However, sleeping bags do not produce any heat on their own. They work by trapping air and then your body heat warms up that air (in the same way as a wetsuit with water). If you are wearing too many clothes then your body heat cannot warm up this air and you will not be getting the full benefit from the sleeping bag. So instead I get into my sleeping bag in my underwear and allow my body to warm up the trapped air. If it’s a cold night then I will wear a set of long johns, a base layer top, a pair of socks and a hat. Make sure these clothes are dry (see point 5)!

To stop all of that nice warm air escaping every time you roll over most sleeping bags come with draw cords and baffles around the shoulders and face. I tighten the ones around my shoulders and leave my face exposed.

4. Warm up before you get into your sleeping bag.

Remember sleeping bags don’t generate heat, they just trap it - so if you get in cold, you will stay cold! There are two ways we can warm up. Firstly we can exercise briefly just before getting in. A few push ups or star jumps will increase our body temperature, just avoid building up a sweat! Secondly we can have a warm drink or some calorie rich food which will increase our metabolic heat, like putting wood in a furnace. An ‘Old Timer’ trick was to stick a knob of butter in your hot chocolate...its surprisingly tasty!

5. Dry=Warm.

You need to make sure that your sleeping bag stays dry, so that means carrying it in a dry bag or a couple of bin bags (top tip: twist the top of the bin bags to seal, don’t tie. That way you can re-use them and not have to struggle undoing a knot.) and protecting it from moisture when its laid out. It is very, very tempting to bury your head into the sleeping bag on a cold night, but all the moisture you exhale will collect in your bag and drastically reduce its insulative qualities. If you are suffering from a chilly nose, try putting on a Buff. You also need to make sure that any clothing you wear in your sleeping bag (see point 3) is dry and hasn’t accumulated sweat or moisture during the day. I often carry an old set of base layers to use as pyjamas.

Even if you keep your bag dry and avoid the temptation to bury your head inside, your body will still produce about 300ml of moisture through insensible perspiration. This is the moisture required to keep your skin health and happy. Imagine taking a couple of sips from a drinks can and pouring the rest over your sleeping bag. At every opportunity it is important to air your sleeping bag somewhere with a good airflow and ideally some sunshine. I usually sling it over my tent on a dry morning while I’m cooking breakfast and packing up. If it’s a wet day then you’ll have to wait for the sun to come out!

This article was written for Adventure Breaks by Ross Bowyer. Ross is a TV Survival Consultant and has worked with the likes of Ray Mears, Bear Grylls, Ed Stafford and James Cracknell. You can follow Ross on Instagram here.

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