Testing: Rewarming Drill

SITKA’s Senior Product Manager of Hunting, John Barklow, teams up with SITKA Ambassador Adam Foss at the GORE Lab for a worst-case-scenario rewarming drill. After full cold-water immersion to simulate getting wet in the field, they don the Hyperdown jacket and pant, then transition into a Hyperdown sleeping bag to reverse heat loss. To track the process, they swallow RFID chips to log core temperature, pulse, and heart rate while the lab records additional metrics. This is an extreme, controlled test—do not try this at home. The initial minutes are brutally cold, with aggressive shivering, numb hands, and dampness setting in. The rewarming sequence is straightforward: stop heat loss with “puff” layers, seek shelter (bushes, trees, rocks, or a tent), get into the bag, and boost heat with warm drinks and food. Clothing is the first line of defense, and the body’s metabolic engine helps push moisture out when fire isn’t an option. A practical add: boil a liter of water, pour it into a bottle, and place it in the sleeping bag to warm feet. About an hour in, the shivering subsides and they stabilize; moisture can be seen moving through the bag. The takeaway: modern, treated downs have advanced—there’s still loft after something this extreme. In their words, Hyperdown is “the warmest and best insulation” SITKA has made, and this is “the best system” they’ve tested. The focus isn’t on individual pieces, but on assembling a technical clothing system that works together when conditions turn.