Nemo Disco 15

Anyone who sleeps on their side knows the specific frustration of a mummy bag: the shape is optimised for warmth-to-weight, and warmth-to-weight is optimised for someone lying flat on their back. The Disco is one of the few bags we’ve tested that actually solves this rather than just padding the problem — the spoon-shaped cut gives genuine room at the hips and shoulders for a side-sleeper to roll and resettle without fighting the bag’s own geometry all night.

The detail that elevates it beyond “roomier mummy bag” is the pair of zippered thermal gills across the chest. Unzip them on a milder night and they dump excess heat almost instantly, which matters more than it sounds — most down bags force a binary choice between “too warm, unzip fully and lose the insulation” and “correctly warm but slightly clammy.” The gills let you fine-tune in a way that feels obvious in hindsight and genuinely clever the first time you use it. Zip them closed as the temperature drops and the bag reverts to full mummy-level warmth.

We’ve taken this down to temperatures close to its quoted comfort rating on exposed highland camps, and it has held up honestly — cold mornings were cold, but not the bag’s fault, and the 650-fill hydrophobic down resisted the damp better than untreated down would in the same conditions, though “better than untreated” is not the same as “immune to it.” In a genuinely wet tent over several nights, loft does start to suffer, same as any down bag without a full waterproof shell.

It’s a touch heavier and bulkier packed than a top-end quilt aimed at the same temperature range, which is the trade-off you’re making for the enclosed, warmer structure of a full bag with a hood. If you’re chasing the absolute minimum pack weight and sleep warm regardless of position, a quilt will serve you better. If you’re a side- or restless-sleeper who has spent previous trips fighting a mummy bag at 2am, the extra weight buys real, noticeable comfort.