Bikepacking essential: Review of the Therm-a-Rest Hyperion 0C UL sleeping bag

Did you know? The modern, inflatable outdoor sleeping mat was invented by three former Boeing engineers: Jim Lea, John Burroughs and Neil Anderson. They developed the first prototype of a self-inflating sleeping mat in 1971. This led to the creation of the world-renowned company Cascade Designs, with its flagship brand Therm-a-Rest.

However, Therm-a-Rest doesn’t just offer sleeping mats; it also has sleeping bags in an ultralight pack size.

The Hyperion 32F/0C sleeping bag

The Down sleeping bag It is one of the lightest in its class and is therefore ideal for outdoor enthusiasts who are particular about every gram. Its thermal chamber construction is designed to ensure warmth in the key areas whilst also offering comfort, all whilst keeping the weight to a minimum.

The sleeping bag is available in two versions: the 0 °C version we tested and the -6 °C version. This figure refers to the ‘limit’ temperature. More interesting is the ‘comfort’ rating, which is 5 °C for the model tested. This means it is a three-season sleeping bag. It is almost too warm for balmy summer nights.

We tested our model on a bikepacking tour in Germany lasting a total of eight nights, as well as during an outdoor event in Greece in October.

Packaging artist

Thanks to its matching compression bag, the Hyperion 32F/0C packs down impressively small. Equally impressive is its weight of just 506 grams including the stuff sack – and this is not a hut-only sleeping bag, but a three-season sleeping bag whose insulation keeps you warm even in autumn temperatures.

When it comes to weight and pack size for bikepacking, I’d therefore give it full marks. The 900 cuin Nikwax Hydrophobic down is said to stay dry and fluffy for longer than untreated down. As a bit of background: down still offers the best warmth-to-weight ratio.

​This is what it’s like to sleep in the ​Hyperion 32F/0C Regular

What stands out when compared to standard sleeping bag models is the zip, which does not run all the way to the bottom, and the two straps for attaching it to the sleeping mat.

The fabric of the Hyperion feels comfortable against the skin. I haven’t tried out the two straps for the sleeping mat. The non-full-length zip takes some getting used to. Particularly in mild temperatures, I would have liked to be able to pull the zip right down and use it to cover myself up a bit more. Still, thanks to the 2-way design, the zip can be pulled right up to the top and opened at the bottom at stomach height.

Features of the Hyperion 32F/0C UL

• Ultralight: Hyperion is one of the lightest sleeping bags in its class. 506 grams in the Regular version (including the stuff sack)
• 900 cuin Nikwax Hydrophobic Down™: Stays dry for longer and retains its fluffiness 60 times longer than untreated down.
• Compact when packed: Thanks to lightweight materials and a well-thought-out design, the sleeping bag can be compressed into a small size.
• Chamber design: Featuring mesh panels for ventilation and heat distribution in key areas.
• SynergyLink™ Connectors: Connect the sleeping bag to a mat. The connectors can be removed.
• Isolation zones: Maximum warmth combined with a lightweight design, achieved through the functional distribution of the filling material: 70 per cent at the top and sides, and 30 per cent at the back.
• Certified in accordance with the Responsible Down Standard: This certification guarantees that the waterfowl from which the down is sourced are reared in a manner appropriate to their species.

The sleeping bag costs 525 euros, but it’s available online at a significantly reduced price >> for example, at Mountain lovers or Bike24.

​Verdict on the Therm-a-Rest Hyperion 32F/0C UL

The Hyperion 0°C three-season sleeping bag It gives the impression of being very high quality. Its packed size and weight are unbeatable and ideal for bikepacking. You can tell the down is top-quality. A nice bonus for your conscience: the Responsible Down Standard certificate guarantees that the birds from which the down is sourced are kept in a humane manner. There are some criticisms, however: the Hyperion 0C’s zip isn’t full-length. This is a bit of a nuisance in mild temperatures, as it can get quite sweaty. The head section could be a bit larger.
Laurin Lehner, BIKE tester