It is probably best not to consider a sleeping bag as your only bedding, but consider it to be part of a ‘sleep system’ incorporating liner, pyjamas, down blanket or clothing and perhaps even a bivvy bag (used inside a tent) for additional warmth in the colder months. The type of mat you use will also be a factor in how well you sleep and how warm you are.
The starting point is your sleeping bag. The kind that offers the greatest warmth compared to its pack weight will always be a down filled bag. Unfortunately down bags are more expensive, but the weight difference between down and synthetic filling can be considerable. Goose down provides better insulation pound-for-pound than duck down and is consequently more expensive still. Alpkit’s Skyehigh bags costing around £160 have long been something I have lusted after but not been able to afford. It is possible to find cheaper down bags though, ours cost just £55 each in 2017, bought from an eBay seller who was off-loading bankrupt stock.
These sort of bargains are hard to predict, but you can find them sometimes on eBay if you are patient. When searching for a down bag this way you should be wary of any that say they have been stored in the stuff-sac, as this can damage the ‘loft’ of the bag and damage the heat retention properties. People seem to add ‘has been stored in its stuff sac since day one’ as some sort of selling point, when in fact it is the opposite. Down bags should always be stored hung up, fully unpacked.
Make sure you know the weight of the bag before purchasing – they vary enormously. Ideally you would choose one with hydrophobic down filling, meaning it had been treated to minimise moisture absorbtion, but as this is a fairly recent innovation these tend to be more expensive. Its not essential, but it is nice to have as it means a warmer night and a lighter bag to carry in the morning, it also should mean less airing to prevent it going smelly on longer trips.
We use 2 / 3 season bags weighing around 800g. Obviously the warmer the bag, the heavier it will be, but some bags are heavy because they use cheaper material, zips and so on which add to the weight. There are a lot of Chinese manufacturers selling very cheap down bags now via eBay or Alibaba. Some people say they are great, but you should be wary of stated weights, temperature ratings and fills. If your budget is very low and you have time to wait for them to arrive then they are a good option though.
Sleeping bags come with three temperature ratings. I ignore the lowest two and focus instead on the highest as this is the minimum that you can enjoy a good night’s sleep. Ours have a rating of 3C – this is a good bag for summer and the shoulder months. It can also be comfortably used in much lower temps by utilising other layers in your sleep system. We have slept out in sub-zero temperatures in ours quite comfortably.
As down is challenging to wash, you should always use down sleeping bags in conjunction with a liner. We use a thick liner in cooler weather and a thin, lighter weight one in summer. For a thin lightweight liner that has a very small pack size and is quick to dry once washed, silk or faux silk is the best choice. The cheapest silk liner I have found comes from Decathlon at £25 each. Faux-silk liners are about half this price. We have one of each and to be honest I can’t tell the difference. Both weigh around 150g. If the weather is very hot then you can unzip your sleeping bag and use it as a blanket over you inside the liner or just sleep in the liner alone. For colder times we use Lifeventure thermolite liners. These are a sort of t-shirt type material but perhaps lighter in weight. I don’t think they increase warmth by as much as is claimed, but they are still pretty cosy. They weigh 370g each and I think they cost me about £12 each – new on eBay, though they seem to be a lot more expensive now.
We use merino wool pyjamas as they are very warm without causing you to overheat, lightweight with a small pack size and are naturally anti-bacterial so they don’t go smelly for ages. If you chose well (ie dark leggings and a plain top) then they come with the added benefit of being clothes that you can wear outside to ride or socialise in if the need arises (ie when you want to wash all your other clothes on a long trip, but don’t want to sit naked in the laundrette).
We have a down blanket each which we use to top up our sleeping bags in very cold weather. They are fairly bulky and weigh 350g each, so they only taken with us in extreme conditions. I have successfully used one of these on its own as a very lightweight sleeping bag in hot weather. Ours were from eBay at £20 each, but down blankets can cost many times more than that. Ours were a type that used to be sold by Costco as a down throw, but they don’t sell them any more. They tend to slip off in the night so are best used inside a bivvy bag or fixed to your sleeping bag somehow.
Initially we used Apkit Hunka bivvy bags. If you are not sure about using one and want to try it out then these are a good, low cost option. It is always best to get a bivvy bag that is big enough to fit all your sleep system including the mat inside as a lot of heat will be potentially lost through the mat otherwise. It makes a really big difference on a cold night to have the mat inside, plus it keeps the mat clean and away from sharp hazards if you sleep in the bivvy bag without a tent (as you are meant to!) We mostly use ours to keep us warm inside our tent in very cold weather, though you will get a build-up of condensation inside by morning however breathable they are said to be. For these reasons, I wouldn’t recommend the smaller Hunka bag, but the XL size is good for both mat and you inside your sleeping bag. The weight of these is around 400g though and they are fairly bulky so I have now traded up to Borah gear bags at 250g. These cost $95 ordered from the US, so I had to pay something like £20 to the post office for import duty too. They are much more compact than the Alpkit bags and also have a midge/mosquito net for use outside. We carry these and a small lightweight tarp for our bothy trips, in case a bothy is full on arrival or we don’t make it there for some reason. They are dark in colour but otherwise make a really good survival bag if you are heading to wild places. (Photo courtesy of Borah Gear).
We use Exped mats – they are tough, hard-wearing, lightweight with a small pack size, and most of all they are very comfortable. They weigh just 365g. We used to have the down-filled ones, but I don’t think it actually makes much difference warmth-wise in exchange for the extra weight and bulk. Here are our mats packed – Tunnocks tea cake for scale….
….and pumped up ready to use… the yellow bag is the ‘schnozzle’ pump. It is also a useful lightweight drybag for keeping your gear dry en-route.