Therm-a-Rest Hyperion 0C/32F Sleeping Bag

The Hyperion weighs in at 567g/1lb for the 0°C/32°F version and 545g/1lb 4oz for the -6°C/20°F option, making them some of the lightest bags in their class. 

The shell and liner of the Hyperion are made from 10D Nylon RipStop, with the shell featuring a DWR finish. They are tailored for a comfort-fit, using an ergonomic shape and a half-length zipper to offer easier entrance and exit from the bag while keeping drafts to a minimum.

The insulation used in the Hyperion is RDS certified Nikwax Hydrophobic Down™ which stays drier and maintains loft 60 times longer than untreated down.  When compared to untreated down it absorbs 90% less water and dries three times faster. Performance is maintained through 5 wash cycles and can be fully re-treated with Nikwax Down Wash Direct®.  Nikwax Hydrophobic Down is free from PFC’s and the water-based formula is safe for both you and the environment.

The RDS certification ensures that the goose down used is traceable and is sourced from the most ethical and sustainable supply chains in the down industry.

Box Baffled Construction has been used in key areas of the Hyperion Sleeping Bag in order to increase thermal efficiency. This is done by separating baffles with mesh walls on the interior of the bag instead of stitching through both the shell and liner which creates thin spots in the bag.

Zoned insulation keeps the warmth to weight ratio high by strategically placing insulation. 70% of insulation is located on the top and sides, while the remaining 30% reside on the bottom, or back, of the bag.

Shell Fabric: 10D Nylon RipStop with DWR finish
Liner Fabric: 10D Nylon RipStop
Insulation: Nikwax Hydrophobic Goose Down (RDS certified)

• Ultralight and packable
• 900 fill-power Nikwax Hydrophobic Down
• Box Baffled Construction
• Comfort-Fit
• SynergyLink Connectors
• Zoned Insulation
• RDS Certified Down

The Therm-a-Rest Hyperion Ultralight Down Sleeping Bag is well thought out, has great thermally efficient, excellent compressibility, and a nice simple/clean design. It’s also a reasonably priced, ultralight sleeping bag.

Perhaps the most notable feature of the Hyperion is its focus on insulation design. The use of mesh walls within the baffles to mitigate cold areas along the stitching is a really simple solution to a common design flaw. Zoned insulation is another key design feature that enhances the warmth to weight ration. Insulation under the body is compressed and therefore lacks any significant loft, but with zoned insulation, the insulation is strategically located to remain lofty and retain body heat. The use of Nikwax Hydrophobic Down is a big win as well, by not only offering water resistance but also the ability to reapply the treatment in the future.

Another key feature of what makes this bag really great is its compressibility. When fully compressed, the bag isn’t much bigger than a 1L water bottle. When it’s time to store the bag, a quality storage sack will help to maintain the performance over time. Having both these bags included with the purchase is not uncommon, but is always appreciated. 

The only complaints I have with the Hyerpion is the lack of a built-in zippered pocket to store earplugs or a headlamp and the fact that the sizing is a little tight. Neither is a game-changer, but instead just something to take note of. 

The bag’s reduced size is something that’s hard to avoid in an ultralight bag. More room in the bag means more material and more weight. The Hyperion is still comfortable, but it could be a deal-breaker for those who feel claustrophobic in tight sleeping bags. An alternative would be something like the Sierra Design Cloud 800 although this is almost 50% heavier but does offer a roomy sleep experience. 

The SynergyLink Connectors are a thoughtful touch for those nights when the ground is slightly sloped and you find yourself slipping off the mattress. My only thoughts regarding this feature are that the SynergylLinks will only fit around smaller pads but if you’re going ultralight, chances are your pad will be small enough for the SynergyLinks.

On the whole, the Hyperion Sleeping Bag is a great piece of equipment. The small packed size is perhaps its greatest advantage, not to mention weighing in at less than half a kilogram! 

If you are looking for other Therma-a-Rest sleeping bags then check out our reviews of the Oberon Sleeping Bag (which won our Gear of the Year Award), the Antares Sleeping Bag, and the Vela Double Down Blanket.