The Pros of Down Sleeping Bags

Down insulation is made from extremely soft bird plumage. With these feathers acting as natural insulators for the birds themselves, it’s no wonder they’re often used in the manufacture of apparel.
Down clusters are three-dimensional, fluffy, and light. This allows them to trap the heat emitting from a body into a series of pockets. The most common types of down used for sleeping bags are goose and duck down.

The way down works when it comes to insulation is by trapping the air inside. This is why it’s so effective, and this is why it’s also incredibly easy to compress. It gets you great breathability and is rather durable, especially when you factor in the competition. And for this reason, if your priority is great performance in cold or dry conditions, or you want to save space and reduce weight, down is undoubtedly the better choice.

Another advantage of these sleeping bags is their longevity. High-quality down is capable of retaining its insulation properties for a long time, even with frequent packing and unpacking.

Highlights of Down Insulation

• Compressible
• Lightweight 
• Durable
• Better warmth-to-weight ratio

Down sleeping bags can be easily compressed into a stuff sack. Much more so than synthetic sleeping bags. Between that and their light weight, it's easy to see why down sleeping bags are favored amongst backpackers.
Its warmth-to-weight ratio is unbeatable too. It takes much less down than synthetic material to fill the same area because it lofts more. And it insulates better due to its structure of fine, branched filaments. This is also why down bags are so light compared to synthetic ones. While advances are being made in the world of synthetic materials, there are still none that compare to the insulating properties of down.
With proper care, down is also much more likely to keep you warm for years to come. Decades, even! So, if you're looking to keep the same bag for a while, you can't beat down. It's a worthwhile investment.

When storing down sleeping bags, either hang them or use a mesh storage sack to keep the down as uncompressed as possible. This will ensure that you down sleeping bag lasts for decades.

Since down is so lightweight and compresses well compared to synthetic sleeping bags, it's easy to see why its the top choice amongst many backpackers.