Rest is as Essential for survival as food. A good night's sleep can offset much of the worry and stress of a difficult situation. Making sure your helter is suitable for the environment you're in, and choosing the right sleeping bag, can be vital factors in survival.

Sleeping Bags
Although there are many different shapes and styles of sleeping bag, the one you choose should have enough padding to keep you warm at night even without a tent. A sleeping bag must never be allowed to get wet, so always keep it inside a waterproof cover, such as the bag's stuff sack or a bivy sack. Always try a sleeping bag before you buy it. If it's too snug, it will be less effective.

1. Locking mechanism: keeps the hood closed in cold weather and can be loosened in milder climates
2. Accessory pockets: can be used to secure essential items such as keys or wallets
3. Loops: allow you to attach sleeping bag to the sleeping mat
4. Box foot creates a mummy shape and is designed to conform to the position of your feet when you're sleeping on your side
5. Extra baffles: often added to the foot section to help eliminate cold spots. The foot area should be big enough to allow you to move your feet comfortably
6. Baffles: are channels sewn into the bag to prevent the down from collecting in one area
7. Zipper: ideally it should be snag resistant and have a draft tube to prevent heat from escaping and cold air from seeping in

Down or Synthetic
Sleeping bags are made with either a down or a synthetic filling. Down is made up of highly specialized insulating feathers, normally from ducks or geese, and is unsurpassed when it comes to a warmth-against-weight ratio. However, it is ineffective when wet and can cause an allergic reaction in some people. Synthetic fillings range from simple hollow fibers all the way up to complex fibers designed to mimic the structure of down. They still retain some of their insulating capacity if they get wet.

Tips on Buying a Sleeping Bag
There are many types of bag available. Here are a few things you should consider to ensure you buy the right sleeping bag for you.

• Determine the lowest temperature you're likely to encounter on your trip and choose a bag that will perform at this temperature.
• Synthetic bags are cheaper and easier to clean than down bags, and continue to provide insulation even when wet.
• Down bags are more expensive than synthetic bags, but provide a better warmth-to weight ratio and last longer.
• A mummy-shaped bag provides better insulation than a rectangular-shaped bag, but has less room to move around in.