Marmot Atom Sleeping Bag: 40 Degree Down

Kept my pack down to forty-five pounds on a climbing trip into the Sierras this summer with the help of this lightweight, but warm bag. I was skeptical at first as it seemed so small and thin, but temps dropped down into the thirties several nights and I was plenty toasty in this well-made bag.

I also purchased this bag for 3-season backpacking and I'm very pleased with the product. I have used it 6 times at different morning temperatures and the 40 degree rating is about right - if you're in a tent. I sleep reasonably warm, and when the temp was below 40 I got cold. Above 40, in a tent, I have been fine. Above 50 you will be unzipping it. I don't sleep in anything except a polypro shirt and underwear, liner socks, and a wool beanie, so if you add a layer of thermal underwear, you can decrease the minimum temp. As SpriteMV says, the bag compresses very well. I can stuff it in the bottom compartment of my pack and still have room for my tent, footprint, and camp shoes. Try that with any other bag! The zipper is a bit on the small side, certainly not a #10, so be careful when using it. There is a draw-string hood which works well. Overall, if you want to shave a couple of pounds from your basic gear set for 3-season camping, the Atom is certainly the ticket.

The Marmot Atom is hands-down the best 40 degree bag out there. I purchased it to replace my 25 degree bag during warm weather camping and could not be happier. Before purchasing the Atom, I used to overheat and often ended up sleeping on top of my bag. Those days are long gone! Even in considerably warm temps, I have found this bag regulates my temperature well and breathes phenomenally - I have yet to even hang a leg out of the zipper. Speaking of which, the zipper does not extend all the way to the bottom of the bag, so if you are one of the leg-hangers out there, this may be something to think about. The shell material is absolutely amazing. It is incredibly light and it feels like silk! It also does a decent job of shedding water from the bag to preserve the outstanding loft of the down. As an ultralight junkie, my favorite thing about the bag has to be its packed size and weight. I easily compress it to the size of a cantaloupe, but it could be forced even smaller without much effort given the right compression sack. Marmot does include a stuff sack, but unfortunately it does not have any compression straps. To really take advantage of this bags packability, you will need to find an extra-small compression sack elsewhere. Search around for the smallest one you can find, because this bag _will_ fit in it. I admit, this sleeping bag is a bit pricey, but it is currently the best 40 degree bag money can buy. If you can afford it and are sick of sleeping on top of your overkill sleeping bag during summer backpacking trips, the Atom is a must!

Works as advertised. Pricey but really small.. Works great...

I used the Atom so far just on summer hikes. Last weekend I trusted the weather forecast too much (low: 43F). At 6am it was 30F, and I was wearing long johns, a jacket, and a balaclava and was really toasty in the bag. I belong to the guys who easily freeze. It's the first time I experience a bag getting to a lower temperature than it is rated. I get my Atom, 4-season Therm-a-rest and all my clothes for three days in the lower compartment of my backpack. This sleeping bag is pricy but certainly worth the money.

I've been using Marmot sleeping bags for a decade, and they are well made and last. This sleeping bag is light weight (only a pound!), stuffs small, and is very comfortable. I bought it because my older 15-20 degree bag was always too warm for most of my camping, and I wanted to reduce the weight some. I used this bag several times in the mountains in late spring where the temperature ranged in the low 30's to upper 20's. Though the bag is only rated to 40F, with a silk sleeping bag liner, and wearing silk weight thermal underwear, I was able to sleep well. I was a little cold but I think that was due to the new sleeping pad I was trying out that was bought more for comfort (it didn't have an insulating rating because I suspect it doesn't really insulate). For all my summer trips where the temperatures been in the 40's or hotter, I've never been cold (even with that bad pad). I also haven't been too hot either which was always the problem with my older 3 season bags.

I recently purchased the Marmot Atom to bridge the gap between my REI travel down 45º and my Marmot Helium 15º or Feather Friends Swift 20º epic. At one pound the Atom rocks! I save 13oz from my Helium and over a pound off the Swallow. The REI travel down is actually 8oz heavier than the Atom and likely has more of a 50-55º rating. I have always loved Marmot quality and construction since buying my first Pinnacle 0º in 1992, which by the way is still in near-perfect condition after hundreds of nights. The Atom is built with the best materials and down available. The construction is top notch. I particularly like the hood design which wraps your face with a comfy baffle. At 40º this is a warm, roomy and cozy bag. You could easily push the frost level with a light layer of clothing worn inside. I recently used the Atom at 6,500ft on Mt. Hood on a summer hike. The weather was warm, but it dropped into the low 50's or upper 40's at night. We were at snow level and pitched my tent right next to the slowly fading snow field, which added to the coolness of the night. I was quite happy in my red cocoon. The color is great and adds to a warm tent glow. At one pound I would be hard-pressed to find a better bag! Thanks Marmot!

The bag is not merely for ultralight cranks; I used it on a 5-day early-fall trip in New Hampshire with temps down to approximately 45F. Never cold. The bag was exposed to rain and dirt (never, ever use a tarp) but came through magnificently. The material feels like tissue paper but is very durable. The bag looks new after about a year of use. Loft is incredible; weight savings are great; but the real kicker is the packed size-easily down to Nalgene size. If need be, you could get it to about softball diameter. It starts a chain reaction of smaller (lighter) pack, etc, etc. The Atom is a great bag well worth the money.