If, like me, you’re lazy or live in a small house then it would seem like a no-brainer to just keep your sleeping bags in their compression pouches but this can squish the synthetic or down filling inside them, meaning that it will have less insulation properties.
These should be stored loosely rolled or flat in order not to crush the down and lose the loft (air trapped between feathers).
OK, so you probably don’t have room to do this, so just try to compress the bag as little as possible when it’s stored… and never store in a compression bag.
Washing a down sleeping bag occasionally is a good idea. You will need to use a bathtub filled with warm water to a depth of about 2 inches. Add some soap flakes or Nikwax Down Wash to the water and place the sleeping bag in the mix. Let it soak in for 10 minutes, gently stirring and moving things around occassionally. Then rinse the bag several times, until the water runs clear. It’s best to air-dry a down sleeping bag, occassionally fluffing it up to help lift the loft. You can (with some bags) use a tumble dryer and a couple of tennis balls, but be warned that I’ve killed a down bag doing this.
These are less damaged by being stored in a bag, but even still, avoid using tight compression bags for extended periods. Synthetic loft has more bounce, but you may feel the cold on the first night you use a long-term compressed bag.
Again, try to store a synthetic bag as loosely as possible.
Washing a synthetic bag to get rid of your body oils and dirt will help improve its insulation. Use mild soap flakes or Nikwax Tech Wash in a clean washing machine or hand-wash, and dry the bag according the its label.