Therm-a-Rest Hyperion 32F Ultralight Sleeping Bag
We built the Hyperion 32 for backcountry travelers who count every ounce without sacrificing warmth. At just 1 lb 1 oz (regular length), this ultralight bag uses 900-fill Nikwax Hydrophobic Down™ to keep you insulated even in damp conditions. The 10-denier ripstop shell sheds weight while maintaining tear resistance on rocky bivy sites and cramped tent floors.
We designed the SynergyLink™ Connectors to integrate with our sleeping pads, eliminating the drafty gap between bag and pad that robs heat on cold nights. The tapered mummy silhouette and integrated toe box minimize dead air space, so your body heat stays where it belongs. Whether you're thru-hiking the PCT or pushing into alpine basins, the Hyperion 32 balances packability with three-season performance.
Technical specs at a glance
Down insulation & weather protection
We fill the Hyperion 32 with 900-fill-power down treated with Nikwax Hydrophobic technology, which resists moisture absorption up to 60 times longer than untreated down. The treatment binds to individual down plumes rather than coating the fabric, so loft and compressibility stay intact even after dozens of stuff-sack cycles.
The 10-denier ripstop shell and liner carry a durable water-repellent finish to shed tent condensation and light precipitation. Box-baffle construction keeps insulation evenly distributed across the torso and footbox, eliminating cold spots that appear in sewn-through designs. RDS certification guarantees the down comes from ethically treated birds, audited through the full supply chain.
SynergyLink system & fit
Our SynergyLink Connectors snap directly to the NeoAir and ProLite pad series, anchoring the bag in place so you don’t slide off your insulation during the night. The system adds only 0.3 oz but eliminates the drafty void that forms when a bag rides up or shifts sideways.
The tapered mummy cut follows natural body contours to minimize excess fabric and dead air. We offer regular (6 ft max height) and long (6 ft 6 in max height) lengths, each with a 58-inch shoulder girth that accommodates side sleepers without binding. The integrated toe box uses articulated baffles to maintain loft even when you flex your feet, a detail that matters on sub-freezing mornings.
Packed size & field care
The Hyperion 32 compresses to 6.5 x 10 inches in the included stuff sack, small enough to fit horizontally in a 40-liter pack’s main compartment. We recommend storing the bag loosely in the mesh storage sack between trips to preserve loft—continuous compression breaks down plume structure over time.
In the field, shake the bag thoroughly before each use to redistribute down and restore maximum loft. If the shell picks up moisture, hang it in indirect sunlight or use a low-heat tumble dryer with tennis balls to break up clumps. The Nikwax treatment maintains performance through multiple wetting cycles, but we still advise using a waterproof stuff sack during extended rain or river crossings.
More ultralight sleeping bags from our collection
Rated 4.8 by verified buyers
Common questions about the Hyperion 32F
The Hyperion 32 is rated to 32°F comfort and weighs 1 lb 1 oz in regular length, while the Hyperion 20 is rated to 20°F and weighs 1 lb 7 oz. Both use 900-fill Nikwax Hydrophobic Down and the same 10-denier shell. If you camp primarily in summer or desert conditions, the 32 saves weight. For shoulder-season trips or high elevations, the 20 provides extra insurance.
Yes, use a front-loading machine on gentle cycle with Nikwax Down Wash or another non-detergent down cleanser. Rinse twice to remove all soap residue, then tumble dry on low heat with clean tennis balls to break up clumps. Avoid top-loading agitators, which can tear the baffles. Air drying works but takes 24–48 hours and requires frequent fluffing to prevent mildew.
The SynergyLink Connectors are designed for our NeoAir and ProLite series, but the bag functions perfectly fine on any sleeping pad without attaching the clips. You'll just miss the anti-slip benefit. Some users report successfully clipping to other brands' pads by threading cordage through the connector loops, though we can't guarantee fit or performance.
Higher fill power means each ounce of down traps more air, so 900-fill provides the same warmth as 650-fill with significantly less weight and bulk. A 650-fill bag rated to 32°F typically weighs 1.5–2 lbs, while the therm-a-rest hyperion 32 achieves the same rating at 1 lb 1 oz. The trade-off is cost and care—900-fill down requires gentler handling and costs more per ounce.
We back the Hyperion 32 with a limited lifetime warranty against defects in materials and workmanship. If a zipper fails, a baffle seam splits, or the shell develops premature wear under normal use, we'll repair or replace it. The warranty doesn't cover damage from misuse, animal encounters, or compression damage from long-term storage in a stuff sack. Always store the bag loosely in the mesh bag between trips.
No, the Hyperion series uses a non-mating zipper configuration to save weight. If you need a double bag, consider our Questar series, which offers left- and right-zip models that mate together. For couples using Hyperion bags, many simply sleep side by side with individual bags and rely on shared body heat inside the tent.
The 32°F rating assumes an average sleeper in base layers on an insulated pad. Adding a sleeping bag liner extends the range to about 24–26°F. Cold sleepers or anyone camping in windy exposed sites should add 5–10 degrees to the stated rating. Below 25°F, we recommend stepping up to the Hyperion 20 or layering with an insulated jacket inside the bag.