WINTER SLEEPING BAGS

FWINTER NIGHTS in Britain are not often extremely cold, at least compared to Alpine or Arctic climates. The coldest recorded in Britain is -27°C but temperatures dropping anywhere near that are rare. In fact, temperatures below -10°C aren’t that common and most nights in the hills are in the +5 to -5 range. So for most people, a sleeping bag rated to around -10°C should be adequate for most winter nights. If the temperature does fall much lower, warm clothing can increase the warmth of a bag considerably. This said, those who sleep really cold might well do better with a bag rated to cope with colder temperatures

Rating standards (see box) are useful for comparing bags but should only be taken as an approximate guide. Those who sleep warm may find them understated; those who sleep cold may find them disappointing. There are other factors that determine how warm you sleep too, especially your sleeping mat. If this is inadequate you might be cold even in higher temperatures than the bag’s rating as much heat will be lost to cold ground. Your shelter matters too. A double-skin tent with a solid inner is much warmer than a tarp. Also important are the clothing you’re wearing (remove anything damp!), how cold you are when you get in the bag (it’s easier to stay warm than to get warm) and how recently you’ve eaten.

Winter sleeping bags are usually mummy-shaped with hoods and a tapered body. Close-fitting ones are the most thermally efficient but may feel restrictive. There won’t be room for wearing thick, warm clothing in them either – however this could be draped over the top if needed. Roomier bags are generally more comfortable, but you may feel cold spots when you move in them.

The weight of a bag doesn’t determine its warmth. Heavier bags have lower fill power down and often thicker shell fabrics. But if they’re as lofty as lighter bags then they should be as warm. Their big advantage is much lower cost.

Features

1. Fill

The bags we tested are filled with goose or duck down, which is warmer for its weight than synthetic fill. (Synthetic winter bags