Therm-a-Rest Hyperion 20 Review

Details matter, and the magic of the Therm-a-Rest Hyperion 20 is found in the excellent choice of materials and careful crafting of its features. The luxe 900 fill insulation traps your body heat to keep you pleasantly comfortable all night long, while the well-designed hood can be cinched down to keep the draft collar snugly around your face, sealing it from the cold air outside. For more temperate weather, the two-way half-length zipper can allow some much-needed ventilation for your body's core. All this in in a bag that weighs just 21.4 ounces. With the included compression sack, the Hyperion packs down small enough to get lost inside your pack and may feel so light you'll have to stop mid-hike just to double-check you didn't leave it at your last camp spot by mistake.

Performance Comparison

Warmth

Toasty! Warmth is one of the most important metrics in our review, and the Hyperion 20 is the warmest bag in our lineup. It's easy to see why. It features 12.5 ounces of the finest responsibly sourced 900 fill goose down sewn into its horizontal box baffles using flyweight 10D shell fabric. An excellent 58% of this bag's weight is taken up by the down fill, which is exactly what provides all the insulating qualities.

Our overnight hot water bottle lab test resulted in the Hyperion coming up on top by a fair margin. The 20°F limit rating seems rooted in the real world — if not a little conservative — when we compared the results across all the bags we tested. The smart features found throughout the bag help keep warmth, like the clever and utterly simple pad attachment straps that keep a sleeping pad underneath you rather than wandering away and leaving your bottom exposed to the cold ground.

Weight

We weighed the Hyperion 20 at 21.4 oz — a little heavier than the manufacturer's advertised specifications. Compared to other bags and quilts in this review, this is a good, but not great weight, but it is to be expected for a bag that's rated as low or lower, temperature-wise, than almost every other bag in our lineup.

All the features found in this bag are well-designed and don't take up much of the bag's total weight, especially the very lightweight 10D fabric used for the shell, which is as light as almost every other bag dares to go. Any lighter and you seriously run the risk of premature damage. A similar story can be told about the #3 zipper: anything smaller, and you're asking for trouble. Talking holistically, the designers made intelligent decisions to balance weight with performance.

Comfort

Comfort reigns supreme with the Hyperion 20, not hurt by how much down fill is found within its baffles. The bag's measurements allow for a slightly more relaxed fit when compared to other ultralight sleeping bags in this category. This gave our main 5'11" climbing-obsessed tester a huge sigh of relief, as it's not always possible to fit his shoulders inside some of the more restrictive bags.

We can't help but repeat that all the features in the Hyperion are extremely well-designed and stay out of the way of you enjoying laying in this bag. We especially love the hood. When cinched down, it molds around the sleeper's head and feels comforting and supportive. A draft tube around the hood helps keep cold air from infiltrating. If things get too toasty, you can use the two-way zipper to vent from your hips to your chest while keeping the bag snug against your head, neck, and shoulders if you so desire.

Versatility

Pure versatility isn't the strong point of the Hyperion 20. If that's what you need, consider a quilt, especially one that can transform into a flat blanket and several discrete steps in between. But as ultralight sleeping bags go, the Hyperion has some crafty tricks up its sleeve. Anchoring them all is its generous half-zip two-way zipper, which allows you to get in and pop out of the bag easily and provides multiple ventilation options if things are getting a little too hot.

The 20°F limit rating of the Hyperion means you can utilize this bag well into the shoulder seasons, where a lighter and higher temp-rated bag will fall short. There is a slight weight penalty to carrying a few more feathers than you need some of the time. That said, if you sleep colder than most, this bag could be perfect for summertime use.

Features

We could probably talk about the features of the Hyperion 20 as one does a hand-made watch. Small details go a long way in what we love about this bag. The high-quality materials of the 900-fill goose down and 10D shell fabric are a solid foundation upon which to build a great bag.

The two-way half-sized zipper is one of the best zippers we've found on a bag. We particularly love the position of the top snap at the head of the bag, which allows you to zip up or down any way you want while keeping the hood snug around your face. The cinch strap on the opposite side is out of the way, and stays out of the way, unlike so many other hood cinches we've tested. The bottom sleeping pad attachment straps are so useful and simple that we wonder why every bag ever made doesn't have something similar. We sleep better at night knowing we won't have to be rudely awakened to see just where our pad has wandered off to.

Should You Buy the Therm-a-Rest Hyperion 20?

If you're looking for the créme de la créme of ultralight sleeping bags, the Hyperion 20 rises to the top. The materials are quality, the features are refined, and, dare we say: this sleeping bag is close to perfection. If you can swallow the upfront price, it will serve you well for many miles and years to come.

What Other Ultralight Sleeping Bags Should You Consider?

For a sleeping bag with comparable build quality to the Hyperion 20, look into the excellent Feathered Friends Hummingbird UL 30. It has a similar, more generous girth profile, which should benefit everyone whose trail name isn't prefixed with "skinny." If you don't need as much space in your bag, the Sea to Summit Spark Ultralight 28 is another excellent option. It packs down just as well — or maybe even a little better — than the Hyperion, given it comes with its own excellent compression sack. For a quilt with a ton of excellent refined features, look no further than the Katabatic Gear Flex 22 Quilt. You may consider getting the "wide" option, as we found its main weakness is that the normal option was just a little too tight for our main tester's athletic build.