Therm-a-Rest Hyperion 20 Down Sleeping Bag

$549.95to $579.95
Color: Deep Pacific
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Keep your pack featherweight without sacrificing an ounce of performance. The Therm-a-Rest Hyperion 20 down sleeping bag packs down small and keeps you cozy and comfortable on backcountry pursuits.

Location Image of color Deep PacificLocation Image of color Deep PacificLocation Image of color Deep Pacific
Location Image of color Deep Pacific


  • 900-fill-power Nikwax Hydrophobic Down™ resists moisture and maintains loft up to 60 times longer than untreated down
  • Lightweight materials and precise design allow for a small packed size
  • Thermally efficient box baffled construction uses mesh walls to maximize loft and minimize cold spots in key areas
  • Ergonomic shape and long zipper provide a human-friendly fit
  • SynergyLink™ Connectors integrate the bag with a mattress (not included) for optimal efficiency and comfort; removable for versatility
  • Zoned insulation maximizes warmth and saves weight by intentionally placing fill where you need it most, 70% on the top and sides with 30% on the back
  • Shell fabric has been treated with a durable water repellent (DWR) to resist moisture
  • Storage sack and compression stuff sack included
  • Responsible Down Standard certification ensures that the waterfowl in the down supply chain are treated humanely
  • Backpacker magazine awarded this sleeping bag a 2019 Editors' Choice Award


Many sleeping bags are rated for temperature by an independent testing protocol. REI and the broader industry now use the International Organization for Standardization (ISO) 23537 protocol, which improves on the older European Norm (EN) 13537 standard; you may still see older items in our assortment that were only EN tested. With either protocol, each bag gets a Comfort (or T-Comfort) rating and Lower Limit (or T-Limit) rating. The Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Ratings are based on a person wearing one long underwear layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38. Many brands use the Comfort rating for women's bags and the Lower Limit rating for men's and unisex bags. Everyone's body and sleep comfort differ, and conditions of use (posture, clothing, sleeping pad R-value, wind, humidity, etc.) affect total insulation, so EN and ISO ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth.
View the Therm-a-Rest Hyperion Product LineView all Therm-a-Rest Backpacking Sleeping Bags

Technical Specs

Best Use


Tested Lower Limit

20 degrees (F) - ISO

Tested Comfort

32 degrees (F) - ISO

Temperature Rating (F)

20 degrees (F)

Temperature Rating (C)

-6 degrees (C)


Regular: 1 lb. 4 oz.

Long: 1 lb. 6 oz.




Ripstop nylon

Zipper Location


Insulation Type


Water-Resistant Down



900-fill-power Nikwax Hydrophobic goose down

Fill Weight

Regular: 13 ounces

Long: 14 ounces


Ripstop nylon

Sleeping Bag Shape


Fits Up To (in.)

Regular: 72 inches

Long: 78 inches

Shoulder Girth (in.)

Regular: 57 inches

Long: 58 inches

Hip Girth (in.)

Regular: 49.5 inches

Long: 51 inches

Stuff Sack Size

6 x 8 inches

Stuff Sack Volume

3.5 liters

Compressed Volume

3 liters




Down certified to the Responsible Down Standard (RDS)

46 reviews with an average rating of 4.2 out of 5 stars

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