A sackful of cold frozen death!
November 5, 2011 2:16 AM   Subscribe

Hope me become bivy-savvy! I bought a great sleeping bag... so why am I still cold?

I am one of those pesky Occupiers in my local, temperate city. Because I don't have much time during the week, I like to devote a few nights to staying out with them on the weekend. Recently with this aim in mind I bought a cheap-but-in-good-condition military surplus sleeping bag-- a moderate cold bag, a cover for that bag, and a bivvy sack. The whole arrangement is supposed to, according to the tag, take soldiers down to -30F if necessary. So why am I freezing on nights where the temperature is only 31F?

I know about the layers/no layers debate when sleeping, and currently have opted for stripping out of my big coat and down vest (and using them as pillowing.) So what I might be sleeping in would be something like: tights, jeans, socks, an undershirt, a t-shirt and a sweater. Would I be warmer with less on? Is there anything else I should be doing? To give you an idea of how cold I am, at times I am actively shivering a little.

Your small Southern city Occupy thanks you!
posted by WidgetAlley to Sports, Hobbies, & Recreation (17 answers total) 3 users marked this as a favorite
Most of your heat is lost to the ground. Get a mat.
posted by Busy Old Fool at 2:30 AM on November 5, 2011 [6 favorites]

Cardboard will do as a mat as well. Quite more efficient at heat isolation than camping mats, yet maybe slightly less comfortable.
posted by knz at 3:02 AM on November 5, 2011

Yes, get a foam sleeping mat. And a decent fleece hat. If the bivvy bag is not made of breathable material, make sure you air things out every day, as it will collect moisture on the inside. You can check for this in the morning.
posted by carter at 3:04 AM on November 5, 2011

Best answer: I bivvy quite often in the wild. I've tested the layers / no layers thing, debated it with people more experienced than me and read up on it. It's nonsense! Sleeping bags are insulation, that's all, so more layers = more warmth. And yes, get a decent sleeping mat for underneath you.

Most importantly, your sleeping bag (and the clothes you wear) are like a thermos flask: they'll only preserve the warmth that you've already got. If you want to stay warm in your bag, then get warm first. You're probably cold because you've been sitting around talking a lot with other occupiers, and while it might generate debate, it's not generating much internal heat for you. Get up and go for a brisk walk around the site for at least 15 mins, preferably more before you get into your bag. Brisk, mind you, not a gentle stroll.

You layers of clothes, your bag and your sleeping mat will now be working to keep all that body heat in, and you'll be warmer.

Also, alcohol = colder at night, so if there's a bottle doing the rounds, lay off it. That nightcap won't, in fact, be helping.
posted by dowcrag at 3:14 AM on November 5, 2011 [1 favorite]

You'd be warmer if you didn't wear the jeans, too.
posted by lazy robot at 3:14 AM on November 5, 2011

Ground layer (thermorest), fleece sleeping bag liner and do not sleep in the clothes you were wearing that day- sweatiness etc makes them/you colder overnight. Wear a hat. Wear socks if you want. That's my Canadian sleeping outdoors advice!
posted by bquarters at 6:27 AM on November 5, 2011

Also, go to sleep on a full belly, preferably after a hot meal.
posted by spikeleemajortomdickandharryconnickjrmints at 6:36 AM on November 5, 2011

I tend to sleep cold, and I love the army sleep system, it's so friggin warm! I'm going to second getting a sleep pad, they really do wonders for stopping heat loss. Also, I've found changing my socks before bed helps and if you really want toasty feet you can toss a HotHands pack or two into your sleeping back before your 15 min walk and then slide into a prewarmed bag.
posted by julie_of_the_jungle at 7:06 AM on November 5, 2011 [1 favorite]

Jeans don't provide much warmth. Long underwear, wool or thick fleece socks, a hat and a fleece pullover will help a lot. Definitely get a foam pad or 2 to sleep on. If there's a freecycle in your area, post a request - many people have some leftover foam from carpet padding. Or some old wool blankets. If you have or can get a hot water bottle to fill, it helps take off the immediate chill.
posted by theora55 at 8:03 AM on November 5, 2011

Good advice, but just to be contrarian, you protesting Wall Street not the public infrastructure, tap an extension cord off a street light and plug in a heating pad.
posted by sammyo at 8:39 AM on November 5, 2011

And of course, if there's any way to fill a hot water bottle and tuck it in the bottom of the bag, you will totally have it made.
posted by ottereroticist at 8:40 AM on November 5, 2011

Nthing sleeping mat/pad. Sleeping bag's rated temperatures almost always assume you're including one. REI's instructions say, in addition to the pad "EN ratings are based on a sleeper wearing one base layer and a hat, and using an insulating sleeping pad under the bag."

So yes, you absolutely need a mat/pad. I've used pieces of cardboard in a pinch, and they work much much much better than nothing.
posted by czytm at 8:41 AM on November 5, 2011

Wear a hat! (preferably one that won't be prone to slipping off.
posted by vespabelle at 9:12 AM on November 5, 2011

Hot water bottle, if you're at an occupation organised enough to have a means of producing hot water (or take some in a flask for your first night, at least).
posted by penguin pie at 10:04 AM on November 5, 2011

Best answer: Hat, Mat, and NO moisture. Do not breathe into your sleeping bag, your nose and mouth may get a small chill from keeping them exposed, but you'll freeze if you breathe in/out from your bag. And keep anything wet or damp outside of your bag
posted by njk at 10:43 AM on November 5, 2011 [1 favorite]

To reiterate what others have said, you need a sleeping pad. The reason a sleeping bag, fleece, down jacket, sweater, etc. keep you warm is because they trap a layer of air that, once warmed by body heat, will insulate you from the surrounding cold. If you crush that layer by laying on top of it, you destroy the airspace that would otherwise have provided an insulative layer. So, roughly scientifically speaking, that's why you need a pad. There are a multitude of different brands out there- you may want to consider looking at those that are actually rated with an "R" value to get an idea of how effective they'll be.

A few suggestions:
Big Agnes
posted by EKStickland at 10:54 AM on November 5, 2011

Buy a Thermarest Z-Lite or Ridgerest. $30 and Cascade Designs are an ethical company who make stuff in the US.

Buy it from a local store!
posted by fshgrl at 12:28 PM on November 5, 2011

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