Sleeping bags are part of a portable sleeping system that lets you find a bed for the night wherever you are. Sleeping bags cover the range from a lightweight kid's sleepover bag to a sleeping bag giving you a warm night sleep on a polar expedition.
1. Sleeping Bag Features:
Your ideal sleeping bag depends on your lifestyle, destination, and season. When shopping for a sleeping bag, think about the following
· Shape and size
· Temperature and comfort.
· Outer and inner materials.
· Filling materials.
1.1 Shape and Size
Most sleeping bags range between two basic styles:
· The mummy sleeping bag.
Some sleeping bags are like the mummy-style but with a less pronounced taper and described as barrel or semi-rectangular. The shaped sleeping bags tend to include a hood as part of the design.
Overnight your body heat warms up the sleeping bag and keeps you toasty and comfortable. A mummy-style sleeping bag traps a smaller layer of air inside the sleeping bag, and it warms up quickly, but you have limited movement inside the bag. A rectangular bag contains more air and gives you more room to move about inside the bag. It takes longer to heat up, and more warm air is lost through the top of the sleeping bag overnight.
Sleeping bags can be "regular" – fit most people up to 6' or long for taller people. High-end sleeping bags can fit men or women with tailoring taking account of different shaped bodies. You can buy a couple's sleeping bag to accommodate two people rather than the typical individual sleeping bag. Children's sleeping bags are smaller in length.
The size and shape of your sleeping bag contribute to weight and comfort levels. A restless sleeper camping out in summer may prefer the roominess of a rectangular bag. Most people backpacking in extreme cold prefer a mummy-style for the reduced weight and additional warmth.
An integral hood provides additional warmth by reducing heat loss, and some sleeping bags incorporate a pillow section for extra comfort.
The weight of a sleeping bag depends on the materials and insulating filler. Weight is essential if you are backpacking but less critical when carrying your camping equipment in the back of a car.
Weight is useful when comparing two similar sleeping bags with the same thermal properties. Using a sleeping bag that doesn't provide enough overnight warmth because it is light is a false economy. If you are cold overnight, you won't get enough rest, and you risk hypothermia.
Your sleeping bag needs to cope with the lowest overnight temperature you will experience. Ideally, you pick a sleeping bag with a temperature rating below the lowest expected temperature to give you a buffer zone.
Temperature ratings reflect an average person's comfort level – your experience depends on how warm and cold you feel. Temperature ratings are useful for comparison purposes. ISO or EN are standard temperature ratings. On women's' sleeping bags, you see the temperature rating as a "comfort" level – the temperature at which a cold sleeper remains comfortable. The temperature rating describes a limit rating on other sleeping bags, which is the temperature for a warm sleeper to feel comfortable. If you don't see either 'limit' or 'comfort' as a description or an ISO or EN rating, then the temperature rating is probably a manufacturer estimate.
Always pick a sleeping back for the lowest temperature because you can cool off by unzipping the sleeping bag for some air, but you can't increase the thermal rating.
1.4 Outer and Inner Materials
The exterior materials on most sleeping bags are typically waterproof, or at least water-resistant – rip-stop nylon is a typical outer material. The outer material needs to resist penetration by damp and be durable because a tear means losing the insulating materials.
The inside lining material is typically soft brushed cotton, but you can use a sleeping bag liner of cotton or silk to improve your comfort and keep the inside of the bag clean and fresh.
1.5 Filling Material
Filling material is either down (light and warm) or synthetic. Both insulation types have advantages in terms of warmth and performance.
Down is light, warm, long-lasting, and easy to compress, but you lose all its excellent properties if it gets wet. Synthetic filling wins by being non-allergenic, quick-drying, and remains warm even when wet.