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Do sleeping bags lose their insulation?

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Q:

My Synthetic Insulation Sleeping Bag doesn’t seem to be quite as warm as it used to be. I bought it about nine years ago. Am I crazy? Do sleeping bags lose their insulation? Is there anything I can do to get it back where it was?

Melanie

Portsmouth, Hampshire

A:

First of all Mel, you’re not insane—at least not when it comes to sleeping bags. All sleeping bags and jackets lose their insulating qualities, synthetics much quicker than down. Synthetic bags are generally excellent, but after a few years, the insulation starts to break down and the hollow polyester fibers collapse, losing their insulating qualities. Basically, the more time your sleeping bag spends in a stuff sack or in your backpack, the quicker the fibers lose their insulating qualities. If you only use your synthetic sleeping bag a few times a year, you probably won’t see any change for five to eight years.

On the other hand, down sleeping bags maintain their insulating properties much longer than synthetics. While down filled sleeping bags are much more expensive, they last much longer—often upwards of 20 years. These bags eventually lose their loft because oil, dirt, and sweat. When this happens, a simple washing process removes contaminants and brings the bags back to life.

Unfortunately Mel, there’s little you can do to boost your old Sleeping Bag’s insulation. You might see a small improvement after washing it, but the best course of action is to make it your sofa surfing bag, and pick up a new sleeping bag for camping.