(Content / Images courtesy blueboltgear.com) A sleeping bag keeps you warm and provides a comfortable sleep (important for recovery) during the (very) cold nights at high altitudes. It basically traps the body heat using insulation material to keep you warm. There are two types – 1. mummy bags which fit tightly around your body and can feel a bit restrictive while sleeping. 2. quilts which are more spacious and open at the base (insulation is ineffective when compressed) where you sleep directly on your sleeping mat / pad.
A sleeping bag (especially those for sub-zero temperatures) is generally one of the heaviest and most bulky items in your backpack. It’s therefore important (for those hiking regularly) to invest in a lightweight bag which usually has down or synthetic isolation material offering good warmth to weight ratio. Synthetic has the advantage to be more suitable for wet hiking environments.
Temperature rating
Every sleeping bag has a certain “temperature rating” – the outside temperature at which you will feel comfortable while sleeping in the bag. Choose a bag with the right rating based on 1. season (summer vs. winter) and 2. whether you are a cold sleeper (need extra warmth for comfort sleep). Note however that a lower temperature rating means more insultation which means more bulky and heavy. It’s therefore to chose the right rating for your hike. I have been using a -4C in summers and -12C quilt (blueboltgear.com) in winters which has worked very well in my long ultra journeys.
A damp or wet sleeping bag is useless (no insulation) so it’s important to keep your sleeping bag dry (protect it in a waterproof dry bag) and air it out in the sun periodically to keep you warm and safe in harsh weather conditions.
Sleeping system
A complete sleeping system consists of several component: a sleeping bag gets complemented by a sleeping pad and warm base layer and tent. The sleeping pad protects you from the cold (hard, wet, uneven) underground. A good insulative (high R rating) pad is important in case of a quilt which is open at base. A thicker pad is also important during winter season or higher altitude hikes (snow, ice). A tent protects you from rain and cold wind. Warm base layer clothing (or reusing your puff jacket in my case) provides an extra layer to capture your body heat and give you comfortable sleep at night.
Use a compression sack to reduce the volume while carrying your sleeping bag in your backpack. Bulkier bags might keep you warm at night but take up a lot of space in your backpack. Down insulation with high fill power (HFP) traps more air pockets per unit of volume and is therefore lighter and more compressible / compact while carrying in your backpack.
Assignment
Acknowledge your understanding of sleeping bags and the importance to provide you with a warm, comfortable sleep in cold weather at higher altitudes.
