I’ve been testing the Sierra Designs Nitro 800 sleeping bag all summer and can report that it’s a very warm bag that is lightweight and comfortable. I love my other bag, the zipperless Sierra Designs Backcountry Bed, but when the temps dip down into the teens and 20s, I prefer the added warmth of a mummy style bag. I was excited to see this new offering from Sierra Designs but wondered how much weight it would add. I was pleasantly surprised to see that it weighs 2 lbs, 8 oz. For an EN comfort rating of 15 degrees F that’s a very reasonable weight. The bag is available in 35 and 20-degree versions for even more weight savings. The 35-degree bag weighs 1 lb 6 oz while the 20-degree bag weighs 1 lb 11 oz.
I’ve been using the Nitro bag this summer on four different trips including two at Point Reyes National Seashore, one in Yosemite National Park and one at Lassen National Park. I paired the bag with a Therm-a-rest NeoAir XLite inflatable mattress with an R-value of 3.2. I experienced a variety of temperatures from blustery, cold temps at the coast to typical Sierra chill in the high alpine and warmer than expected temperatures at Lassen. I don’t carry a thermometer but it didn’t get below freezing on any of the trips and probably ranged from the high 30s to low 40s at night. The bag kept me toasty and comfortable with just a t-shirt on in the cooler temps with the zipper zipped up, using the escape hatch for my feet when I warmed up. When the temps were warmer, I left the bag unzipped. The bag only unzips halfway down so it can’t be used like a quilt. I still found that I could just drape it over me on my pad on warm nights. That usually only lasted a short time before the temperatures chilled down. After that happened, I was happy to crawl into the bag. This summer has been warmer than usual so even after four trips, I didn’t experience extremely cold temperatures. I can tell the bag is warmer than my other bags because on the coolest nights I didn’t have to wear anything except a T-shirt, whereas I usually have to wear socks and a fleece beanie at a minimum. I was able to turn from side to side and draw up my knees without feeling constricted. Narrow mummy bags are a deal-breaker for me so this was a key test. The nylon fabric was soft against the skin.
UPDATE: It’s a year later and I still love this bag. It is warm! This plus my NeoAir XLite pad keep me warm to at least the low 30s.
The bag is called a zero-degree bag. Like so many bags, it’s important to read the fine print, especially for women. That’s because women generally sleep colder than men and need a warmer bag. That’s the general wisdom, anyway. It turns out that it’s not so much gender, but size. Smaller people with less mass and density don’t generate and retain as much warmth. Therefore, a man and woman of the same size may need a similar bag. Perhaps it’s better to talk about cold sleepers vs warm sleepers. Bags that only have one rating are usually rated for warm sleepers so cold sleepers would need to add 10-15 degrees to the rating.
The EN rating system, which uses specific methods for measuring warmth, attempts to address the discrepancy of warm vs. cold sleepers with a dual-rating system. It’s important to know that EN tests are based on a sleeper wearing one long underwear layer and a hat while sleeping on a single one-inch thick insulating pad.The EN Comfort rating should be used by cold sleepers. For the Nitro bag, the EN Comfort rating is 15 degrees F. The EN Limit rating can be used by warm sleepers as it’s designed to indicate the lower temperature limit. The EN Limit rating for the Nitro is 2 F. It’s not quite zero, but it is close enough.
A mummy bag is an effective shape for retaining maximal heat without dead spaces or drafts. However, sometimes a mummy bag can feel restrictive to restless or side sleepers. The Nitro has a mummy shape, but it is cut generously enough that it felt roomy even when fully zipped up. One nice feature that they carried over from the Backcountry Bed is the escape hatch for the feet. If the feet are too warm, there is a hidden, overlapping slit near the bottom where feet can be vented.
One thing that can be annoying with mummy bags is a zipper that constantly gets caught in the fabric. The Nitro has a two-inch interface the entire length of the zipper track that minimizes jamming. This is a genius addition. The collar also has a generous five-inch baffle to keep drafts out. A cord allows the collar to be cinched down.
The bag is made with 800 FP Dridown, which is down coated with a special hydrophobic polymer. The Dridown treatment allows the down to stay dry longer, dry out faster when it gets wet and loft better than untreated down.
The regular size fits up to 6 feet while the long size goes up to 6 feet 6 inches.
The bag comes with a stuff sack and a larger mesh bag for storage. I use a Sea to Summit E-vent waterproof compression bag. If I have a lot of space in my pack, I don’t use the compression feature but if I need extra space, I can compress it into a small ball.
The Sierra Designs Nitro 800, 0-degree women’s sleeping bag is a lightweight warm bag that compresses to a small size and is comfortable to sleep in.
All photos by Inga Aksamit, unless otherwise credited.
Disclosure of material connection: I received a sample for testing purposes, but the opinions expressed are solely my own.