The first thing you notice about the Therm-a-Rest Hyperion 32F/0C sleeping bag is the shell’s silky feel. That same soft, 10D nylon fabric is used for the liner and, filled with light and efficient 900-fill Nikwax Hydrophobic Down, the Hyperion’s a luxurious, truly light-weight (just at just 528g) three-season bag. Comfort-rated to 5°C, it’s rated as useable down to freezing: as a warm sleeper, that’s sufficient for me outside winter.

I’d dispense with the supplied compression sack when backpacking. Though well-designed and seemingly DWR-treated (water beads nicely), it lacks sealed seams and is drawcord-closed: water penetrated a seam when held under a tap. A drybag won’t compress as effectively but will keep the Hyperion dry.

John Manning’s Best In Test

The first thing you notice about the Hyperion 32F/0C sleeping bag is the shell’s silky feel.
  • Weight
  • Luxury fabric
  • Synergy link connectors
  • Left zip only
  • SynergyLink Connectors
Quick specs
Price: £425
Weight: 528g (483g + 45g) (Regular)
Fill: 900 fill Nikwax Hydrophobic Down, Responsible Down Standard-certified down
Shell: 10D Nylon RipStop with DWR
Construction: Box baffled construction, with zoned insulation
Zip: Three-quarter zip
Length: 203cm/80 inches (Regular), 216cm/85 inches (Long)
Rating: Comfort 41°F/5°C, Limit 32°F/0°C
Sizes: Small/Regular/Long
Supplied with: Compressible stuff sack and storage bag
Women/Men’s version: Unisex

Therm-a-Rest describes a “longer zip for easier fit” though I’d describe it as three-quarter-length. On 5’7”-me, it unzips to my thighs, sufficient to be used as a blanket on warmer nights. The zip’s on the left – okay for right-handed users, not so much for lefties.

Ever awaken chilled, to find you’ve slid off your sleep mat on to the tent floor? Therm-a-Rest has striven to address that with “SynergyLink Connectors”: two ribbons attached to the bag’s underside, which loop around your mat to prevent slippage. My mat-of-choice – a foam Therm-a-Rest RidgeRest – is a mere 3/8ths of an inch thick and slipped in easily. I found the system something of a curate’s egg: yes, I stayed on the RidgeRest but, when I wanted to sit up and reach for something, the RidgeRest came with me. I also had to ensure the mat was perfectly positioned from the off, as adjustments involved exiting the bag. I like them, though it’s a close-run thing: the bag’s narrow and would normally turn with me in my sleep; the SynergyLink Connectors prevented that, so I occasionally woke with my face buried in the hood. Staying on the mat is critical, however, as only 30% of the bag’s insulation is in the base – a sensible weight-saving, as that area’s insulation’s efficiency is usually diminished by being crushed while you sleep – so SynergyLink Connectors prevail. Just.