Big Agnes Torchlight EXP 0° sleeping bag review: this warm, expandable design was perfect for freezing nights on my trek to Everest Base Camp

Big Agnes Torchlight EXP 0°: first impressions 

Sleeping bags can be warm and technical, and they can be roomy, but they're not often both at the same time, so imagine our surprise when this bag came along touting both characteristics.

The Torchlight EXP 0° from Colorado brand Big Agnes boasts a patented expandable side panel design. This basically means that, in addition to the regular zip along the side that opens your bag up, there's a second, parallel zip, which adds up to 10in (25cm) of space for sleeping on your side or on your back with knees bent.

What's more, this space can be opened up wherever you want it, around your shoulders, hips, knees, feet or along your whole body.

Fully insulated with 650 Fill Downtek PFC-Free water-repellent down, this bag holds up against frigid temperatures, and has a cozy hood to seal out drafts. The shell fabric is silky, soft, and not noisy.

If you're using it with a sleeping pad, the integrated PadLok Sleep System attaches to your pad so you don't roll off. The Pillow Barn allows for natural head movement while keeping your pillow securely in place, and the cozy hood is just like the one on your favorite down jacket.

Though it comes with a carry sack, you need to buy the stuff sack separately, and we recommend that you do, because it's a bit bulkier than your average sleeping bag and, while not the heaviest we've tested, it's definitely not ultralight. It's feasible that you'd take this on a short backpacking trip, but where we think it truly excels is for longer, cold expeditions where you're transporting your gear in a duffel.

Big Agnes Torchlight EXP 0° sleeping bag: in the field 

For the past couple of years, I've eschewed restrictive sleeping bags and favored my Sea to Summit camping quilt, but for the trek to Everest Base Camp, I knew I'd need something really warm. Though we'd be sleeping in teahouses, those teahouses aren't heated, and at elevations of 16,942ft (5,164m), I was warned it could get well below freezing at night.

I also knew my gear would be carried by porters, so while I had a strict weight limit of 15kg to fly to Lukla, I wasn't quite as conservative as I usually am.

I slept with this bag for 11 nights on my trek to and from Base Camp, and have taken it on one ensuing car camping trip in Scotland this summer.

Here’s how it performed:

Comfort and design

This sleeping bag is easily one of the softest and coziest I've ever enjoyed, at least on par with the zipless Sierra Designs Night Cap. The shell fabric is super soft, and the down filling feels quite sumptuous. Even though the beds I was sleeping on during my trek in Nepal came with bedding, including a comforter, the cleanliness wasn't always pristine, and I was quite happy to just throw this over the top and sleep inside it every night.

Of course, the main reason it's so comfortable comes down to its innovative design, which allows it to be expandable, and I used this feature every night. It gives so much extra space that I was able to sleep inside it on my back with my legs crossed in a basket, which I understand is unusual, but hey, it works for me.

I'm a bit of a sprawler, and without the usual restrictions, I got better sleep and never ended up with achey hips like I sometimes get from lying like I'm inside a coffin.

Warmth and breathability

On the trek to Base Camp, I tested these measurables out in some pretty cold conditions, even though I was indoors and not on the ground. With just thin wooden walls, by early evening my room would be too cold to relax in, so I'd usually get inside my bag to recover from my hike before dinner, then get right back in it for bedtime.

Exactly why Big Agnes have called this bag the EXP 0° is something of a mystery, since that number doesn't seem to relate directly to any of the product's temperature ratings, which range from ISO 18°F/-7.8°C for comfort, to 6°F/-14.4°C for limit. It's possible that the bag has an unpublished extreme rating of 0°F/-17.8°C, but we'd never advise using an extreme rating as a guide, since that is a temperature at which you might well survive in a bag, but could be risking hypothermia - you can learn more about sleeping bag temperature ratings here.

However, all that said, the Big Agnes Torchlight EXP 0° sleeping bag is incredibly warm. Even in the challenging conditions described above, I was often able to unzip it a bit, so I wasn't anywhere near the edge of the comfort limit, which I had been a little concerned about.

On the other end of the spectrum, it has proven a bit warm for summer camping here in Scotland, but it does come in 20° and 30° ratings if you want something for milder weather, but like the sound of the expandable design. I'd also add here that it's really quite breathable and I've never suffered a sweaty night in it.

Weight and packability

Though this isn't heavy, like an old flannel sleeping bag, it does have considerably more heft and girth than my camping quilt, and I personally wouldn't bring it on a backpacking trip, no matter how much I love it.

That said, it's not super heavy, and I think with a proper stuff sack, it's an excellent choice for serious alpine expeditions where you're transporting your gear to a base camp. Or car camping, of course.

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