The Big Four for cold sleepers

1. A lot of young men have a high metabolic rate, so they burn a lot of calories just sitting around camp, so they seem to stay warmer than the next person. Some other backpackers who feel cold a lot could probably do a few easy things to speed up their own metabolism. One thing, of course, is to exercise daily, and I don't mean just strolling around the block.
2. When you do go up to the mountains during mostly normal weather, remember that if you can stay absolutely dry and blocked from wind, then it is not difficult at all to stay warm. As soon as you get sweat or rain or wind under your layers, it immediately becomes a real job to solve that cold problem. Cotton clothing tends to be bad, and synthetics tend to be better. Down and fleece can be your friends.
3. If you get cold in camp, then I recommend you think more about campsite placement. Know that warm breezes from the valleys rise during the day, and cold breezes from the peaks descend at night. With that in mind, you figure out where the cold breeze will hit and block that somehow. Camp in the middle of the grove of trees.
4. If this is the Sierra we are talking about, a good fluffed up +15 bag ought to be fairly sufficient in summer. That assumes that you are in some kind of windproof tent, you are using a good mattress pad, you have at least a good base layer of night clothing, and that you ate a good hot dinner meal.

A woman friend figured out the way to stay warm on a snow camping trip. She always slept in a tent between two men. That works every time. Also, she arranged the dinner meal to be thermally hot and also spicy hot.

It's all a fun game. It's you against Mother Nature.
–B.G.–

Bob, thank you for the reminder that it's not all just about equipment.

Here's some more info to go on…

1. We're all athletes…trail runners and accomplished triathletes. So our metabolism is not zero. That said, I suspect most women's metabolisms are slower than men's, even when the women are very athletic.

2. I don't think we've made poor clothing choices that cause us to sweat/soak our clothes. No cotton whatsoever in our bunch! I bring exclusively wool/down (plus a paclite jacket with giant pit-zips); my friends who are not into wool are synthetic/fleece/down. We don't hike in the down. All that said, we DO carry way too many layers of clothing in our packs, not to hike in, but just to get warm in camp and inside our sleeping bags. All that extra clothing (in my case, mostly layers of wool) is unbelievably bulky.

3. Good reminder on campsite placement. We avoid the cold areas close to steep creeks. But could be paying more attention to avoiding the night breeze down the mountain.

4. We are cooking hot dinner meals and drinking tea with them. I like the idea of bringing some hot spices, though. Next time I'll bring more ginger tea.

However, this post was not just about me/my friends. I was also curious, in general, what are the BEST investments and the WORST investments in warmth, when you consider weight/bulk.

As an example, one could buy an Exped Downmat for 3-season Sierras camping, but is it really worth the warmth per weight that you'd get? For the x ounces and the bulk that the Downmat would cost you, what would be an even better investment in warmth?

This would help me to advise a couple of additional friends (not all women) who are just getting started in backpacking, about what to invest in.

Elizabeth

Synthetic versus wool clothing can make a difference. Synthetic dries quickly, but cools you down while doing so due to evaporative heat loss. I tend to mix synthetic with wool garments, and wear the wool as close to the skin as comfort allows. This way I have at least one layer which isn't wasting my heat to vaporize my sweat. Hopefully I kept cool enough by removing layers that I didn't sweat much anyway of course. :)

If you can keep it dry, high-fill power down is the most efficient. A down mummy bag on a down air mattress would be ideal. To supplement your standard clothing, maybe you could buy or make a cover for both your mattress and sleeping bag which is used only for sitting around camp, and then removed before sleeping to keep dirt and food out of the sleeping area?

If open fires are allowed, sitting between a fire and either a large rock or a reflective space blanket pitched lean-to style can be very warm.

A tent might actually keep you colder if moisture builds up inside.

Maybe eating more food on your trips will help boost your metabolism a little?

I have read that men and women differ a lot when it comes to warmth. A 15 degree bag was tested, and it was comfortable to 16 degrees for men and around 27 degrees for women.

An article about some of the differences – http://www.dailymail.co.uk/femail/article-1254464/The-curse-cold-feet-Why-women-suffer-icy-toes–it.html

Edit: BEST warmth gained on a cold night is a snickers eaten right before bed.

I think the most warmth for weight can be had in a sleeping bag with a really good hood and draft collar, like that found on my Western Mountaineering Antelope. They do an amazing job of stopping air movement inside the bag, and cinching them up really adds warmth.

Next would probably be a simple Ridgerest or comparable foam pad. For similar weight with light inflatable pads, it seems like you get more comfort but not more insulation.

Next, sleeping socks. Cold feet make everything else seem cold. I like fat, fluffy wool, as they do a good job of wicking away any trace moisture and keeping the feet happy.

Next, a light puffy coat. You can stay warm before bed, during midnight bathroom trips, and when you get up in the morning. Stay warm by keeping the warmth in.

Last on the list for me would be a full tent. For me a properly pitched pyramid shelter in a site out of the wind is just as good as a tent, but I'm one of those darn young guys that runs warm all the time.

A friend is an ultramarathon runner, and I know how she stayed nicely warm as long as she was going, but when she stopped, it seemed like her metabolism almost stopped completely.

I'm no expert, but supposedly a woman's average metabolism is about 10% slower than a man's. That suggests that women might be better paced for a long workout than a man who sprints. I guess you have to use that to your advantage.

Personally, I don't fool around with down mats. Normally in the summer in the Sierras, my pack will have a cheap closed cell blue foam piece to form the rest of the contents. To sleep on, it is augmented with whatever warm clothing I don't wear into the bag.

Just because your sleeping bag has a +15 rating, that does not mean that it is guaranteed to give you that much warmth. Some down bags have lost so much loft (due to shifted down) that they always feel cold.

Oh, one last item. If your feet are cold, put on a warm hat. I wear a warm watch cap on over my baseball cap. If it gets windy, the rain shell hood goes up.
–B.G.–

I agree with David; I think that is an excellent summary of ultralight backpacking. If you can sleep comfortably on a closed cell foam pad, then use it. If you want more warmth, consider getting a little bit more pad or a little bit more sleeping bag. Gossamer Gear sells thinlights, which compliment other pads really well. A thicker sleeping bag doesn't weigh much more than a thinner one — you've already included the weight of the nylon and zippers.

I would probably start with the pad. You don't mention what pad you are using now but that is a quick, often cheap way of experimenting. I hike the same areas as you do and for me a Ridgerest (8 oz.) has been fine in the summer. Today I ordered a Ridgerest Deluxe (12 oz after shortening) because the extra 4 oz. will give a better thermal barrier and comfort. One of the few cases of weight addition.

Also, maybe try a sleeping bag liner. Again for a few ounces you may be able to pick up another 5 degrees of comfort. I do this in the winter at times. It also allows you to customize your setup if you hike in different conditions.

Any way of making/buying a quilt that could wrap around you in camp and supplement your sleeping bag?

Clothing. I generally don't get cold but if I needed more warmth when not engaged in physical activity I would likely get a down headcover. Very likely the best warmth per weight.

Another purchase I recently made was a Golite Wisp windshirt. A very wise 2.8 oz. investment to block the wind, even while hiking.

It sounds like you suspect your sleeping pad ins inadequate, Best oz/warmth you could spend in my opinion.

Also, i love to boil water and put it in a nalgene in the foot of my bag on cold nights, stays even a little warm until morning.

Hi Elizabeth,

I live a stone's throw away from Yosemite, SEKI and the central Sierras, and love to go up there. I also get cold too easy.

I find that staying warm is about eating enough calories and drinking hot stuff before bed, and keeping my body from ever chilling to the point that it has to work too hard to get warm again. I am always the one taking expedition weight while all the others have midweight base layers. I take two base layer tops sometimes, midweight and expedition, and have also hiked in fleece pants when it's clear trail hiking and I can get away with it. During the day on a typical three season trip, I generally wear nylon pants and synthetic T, then a windbreaker if temps drop into the 50s; if it's chillier than that, I swap the windbreaker for a light fleece and if it's windy the windbreaker goes over it. When I stop moving for the day I put on the base layer after cleaning up, put on the pants and fleece again, and add a light down jacket. If it gets really cold sitting around socializing I pull out the quilt and wrap up, and put on the second pair of socks I wear for sleeping, then the day's socks go over them for a warm layer.

I"m not ever going to be ultralight. I just accept that. I would much, much rather be warm. I went to alcohol stoves and boil water only meals to shave ounces where I could, just so I could keep carrying the extra weight of the extra layer and sleeping gear. My usual three season setup is about two pounds of quilts and three pounds of hammock, tarp, lines and a few stakes – I'm working on shaving half a pound off that with some new suspension changes. I can get the pack weight, inclusive of food and water, to 24 lbs for 3-5 days, adding a couple pounds with the bear canister, and that's just the way I have to do it. For weekend trips I got a Bare Boxer to take instead of the Bear Vault Solo, dropping the weight even below the Bearikade Scout for short outings.

I don't think any shelter is meant to add warmth except as a secondary gain from keeping you and the insulation dry. Wind chill is entirely avoidable in a tarp if you get good at site selection; I've hammocked in 30-40mph gusts.

My only really general offerings would be a wind shirt – 3-4 oz, and adds a surprising amount of warmth to your system – and down items. Down jacket, down booties. And a warm, fleecy hat. I take a warm hat all seasons, wear a heavy one sleeping when it's colder. A Balaclava (midweight) can be a versatile piece of gear – I hate having it over my face but use it around the neck and over the head.

I disagree regarding the use of quilts as a sleeping bag supplement. I think the best insulating supplement to a sleeping bag is not a quilt but a jacket of down, pile or synthetic fill like Climashield or Thermolite Micro (and also poly long john pants). That's because an insulated jacket can be a good supplement to your clothing in camp before bed or on a frosty morning breaking camp.

My bag is a WM Megalite, with extra torso/shoulder room for extra insulation. Plus that bag has no side baffles so I could shake more down to the top side for cold nights. Versatility is the key in a 3 season bag.

Yes, the Sierra Nevada can have BIG temperature drops. On the PCT from Kennedy Meadows to Olancha Peak, on the big steam in a cattle-filled high valley there is a campsite by the steel PCT foot bridge. The 1st night there last August it got down to 28 F. The daytime high was in the high 70s. :)

Days later at that same site, on the trip back to Kennedy Meadows, the temperature dropped to 25 F. at the camp and down to 16 F (!!) a few miles further down the valley at 7 AM as we hiked out. That's where my long johns for sleeping really paid off doing "dual use". Kinda hard to use a quilt for warmth while backpacking.

I used to have a fast metabolism and thought pads and ground insulation were for wimps, in my 20s… but in my 50s I sure do feel the cold now!

I agree with all the advice about eating and exercise.

Yes to beefing up your ground insulation and limiting wind chill. CCF pads are very efficient and can be combined with something softer for comfort, or you can go the downmat route.

I like a combination of light down trousers and a light box wall down parka (like Nunatak)for sleeping, with a quilt or a spacious bag that allows the clothes to loft. It's great to have the clothing for cold evenings when you don't want to have to get into your bag. Down is your friend and you can learn to keep it dry.

The combination gives lots of flexibility and if cold conditions aren't expected you can leave the clothing at home. Again if there's any chance of wind chill you can combine a quilt with a light bivy.

As far as tents go the one I found that is significantly warmer than the rest is a Stephenson's Warmlite. Real easy to put up with 3 stakes too. The ones with side windows are great for warmer weather too! With a tent like this you can lose the bivy.

Always try to layer up in plenty of time to avoid getting cold. I think it's already been said, but staying warm is much easier than allowing yourself to get cold and then trying to get warm again.

Hopefully this isn't too personal. Since you all are very athletic, what is your percentage of body fat? If you have a very low percentage, you'll be colder than someone with more "natural insulation". At least that's my experience. Lots of beefy people in the north.

Hot water bottles are cheap and work well too.

I forgot to add – gloves! I use glove liners when temps start to dip much below 50F, and add fleece gloves or waterproof winter gloves as season and temps demand.

Now that you've gotten lots of input from warm-blooded men, here's another shivering female! EDIT–oops, Lori got ahead of me!

Here's what I take for insulation when I expect weather down to 20*F or a little colder:

Tent–mine is a Tarptent so it is breezy! I'd rather have a little breeze than condensation, but it does help to pitch it behind some kind of windbreak, such as a thicket of trees. As with any single-wall tent, pitching it under a tree but not in areas close to water nor in areas lower than the surrounding terrain avoids condensation. This also avoids the coldest air, which of course, sinks!

Sleeping bag: Western Mountaineering Ultralight, 20*. At my age, I have to get up several times per night. I've found that if I snug up the draft collar when I get back in, I soon warm up. I've been down to 18* in it, wearing vapor barrier clothing (nonbreathable rain gear), wicking base layer underneath and my Montbell UL Thermawrap on top. I did get cold on the 18* night, but that was because I was trying to use a NeoAir with a thin supplemental pad–I was shivering underneath and almost sweating on top! Any colder, I'd want a warmer bag, like the WM Versalite.

Pad: I tried a NeoAir for a while, found it uncomfortable and, above all, COLD! (See previous paragraph.) I would not use one below freezing again without a 3/8" to 1/2" CCF pad with it, which definitely eliminates any weight savings over an insulated air pad. My POE Insulmat Max Thermo (predecessor of the Ether Thermo 6) will take me to the mid-20's F. Below that, a torso-length piece of 1/8" Gossamer Gear Nightlight Pad seems to do the job. If I were winter camping, I'd want a down-filled mat of some sort, and I may yet get one. Being old, I need all the cushioning I can get to relieve the pain of arthritic joints. Do consider a warmer pad before trying anything else!

Clothing:
Base layer: I also use it for sleeping. In summer, Capilene 2. In shoulder season or in the high Rockies, I take Capilene 4 bottoms because they're a lot warmer in an area where I need it (it's often my hips that get the coldest).

Hiking shirt and pants–normally nylon (repels bugs better). I normally do not sleep in these, in order to keep the sleeping bag cleaner. When it's not buggy, my base layer top becomes my hiking shirt, in which case I wear it to bed, but normally something over it, such as my wind shirt.

Montbell UL Windshirt. Normally enough to keep me warm while I'm actually moving. I try to keep cool enough not to sweat while I'm hiking. If it's really cold and windy, I will put on underneath it my

Lightweight fleece (Montbell Chameece, lovely cuddly stuff) vest.

Montbell UL Thermawrap. This goes on over the other stuff the instant I stop. It's important to get the extra insulation on right away when stopping, before you get chilled.

Rain gear. I use nonbreathable silnylon rain shirt and pants. That's because I seem to sweat just as much inside breathable gear as nonbreathable. If it's warm, I leave the rain gear off and just get wet (my body heat will dry shirt and pants in 15-20 minutes anyway, and I put on the rain gear when I stop). If it's cold, it doesn't seem to matter; it's more important to have the bare minimum insulation underneath so I don't sweat inside while I'm moving. Best of all, this gear acts as a vapor barrier suit–I wear it over my base layer inside the sleeping bag when the temp is below freezing, to prevent condensation of body moisture on the inside of the outer shell of my sleeping bag. Everyone seems to have their comfort zone for a vapor barrier; for me it's about 35*F while others report the sauna effect at 0*F. If I need more clothing inside the sleeping bag, I put it on over the rain suit so it won't get damp from my body moisture.

Hat: Manzella polypro fleece balaclava. This goes on first if I get cold. If it's really cold at night, I put it over my mouth and nose to warm the air I breathe while sleeping. It dries almost instantly in the morning and means less condensation from my breath on the sleeping bag. While moving, I often wear an insulating headband instead to regulate my "thermostat" so my body doesn't get sweaty.

Gloves: The problem with warm gloves is that you have to take them off all the time to do anything, such as lighting your stove. I've found I'm better off to wear a thin pair of polypro liner gloves–I can keep them on and my hands get less cold. I have a pair of MLD rain mitts to wear over the top when it's wet or windy.

Socks: For longer trips I take two extra pair of Smartwool socks besides the one I wear, and try really hard to keep one dry. I also take a pair of fleece sleeping socks, which are nice and cuddly. The wool socks I try to keep clean and dry supplement the sleeping socks or can be used as mittens, whichever is appropriate.

I also take 2-3 pair of plastic bags from my supermarket's bulk bin department (slightly sturdier than the normal produce bags) to wear between socks and shoes when it's wet to keep my socks as dry as possible. They're really helpful when traipsing through wet grass on cold mornings! I normally don't use them on the trail, just around camp.

Suggestions (some of these repeat what those warm-blooded guys have told you):

Techniques:

Start with your tent site–behind a wind break if possible, not in low-lying areas if at all possible, under a tree if possible (check for "widow makers"–dead branches–first!). Remember that a tightly closed-up tent will have more humidity (i.e., condensation) inside, making everything wetter inside and causing your insulation to deteriorate faster.

Put on your warmer insulating clothing on the instant you stop, before you get out snacks, water, etc. You've probably gotten good and warm while hiking; try to conserve that all heat when you stop. Put a hat on first; even if your hair is long and thick you're going to lose heat from your head more quickly (lots of blood vessels close to the surface).

If, during the day, you get what we in the Northwest call a "sun break," stop and air out your sleeping bag and insulating clothing.

A hot cup of tea can work wonders; so can a candy bar. Consider boosting the fat content of your dinners (most dried or freeze-dried foods are almost fat-free) with a tablespoon or two of olive oil mixed in. Nuts and dark chocolate are excellent (high in the good fats). Also, keep hydrated–it's just as important in cold weather as in warm.

If you get chilled while sitting around, get up and do a really brisk hike or calisthenics for about 10-15 minutes to rev up your metabolism and get warmer. If you're wandering around looking for the perfect sunset view, do it briskly! Do the same just before you go to bed, so your body is producing extra heat to warm up the sleeping bag. Rather than sitting around talking after sunset (unless you have a campfire), lie around zipped up in your sleeping bags for evening chats. A "sit pad" helps when you're sitting.

Try a warmer sleeping pad–cheaper than a warmer sleeping bag!

Most sleeping bags aren't nearly as warm as they claim. For example, I had a 30*F (supposedly ) Marmot Hydrogen and started getting cold at 40* in it. Below freezing I was cold even with all my outer clothing on! Western Mountaineering bags have the reputation of being more accurate, if not more conservative, in that we cold-blooded females can trust the temperature rating or even go a little below. IMHO, most of the ratings by US manufacturers are pure fiction. If your bag is rated by EN 13537 standards (http://www.europeanoutdoorgroup.com/downloads/sleeping-bags/EN13537%20Information%20For%20Retailers%20Jan%2005.pdf), be sure it shows the "comfort" rating (supposedly for women) and assume that rating is 5* overstated (i.e., if it's 15*F, figure it's more like 20). Often when a single EN 13537 rating is shown, it's either for men or, more likely, the rating that may or may not keep you from dying of hypothermia!

So far, I've been plenty warm enough in the baselayer top plus vest plus wind shirt plus Montbell UL Thermawrap, plus rain gear over all if it's windy. It really helps having the heavier baselayer bottoms! I've been eyeing the Montbell UL Thermawrap parka (more insulation) or the Montbell UL Down parka (more insulation and as light as the thinner Thermawrap). Either of these (or something with similar insulation and total weight) might work better for you. Insulated pants (synthetic or down) plus really lightweight base layer bottoms might also work better for you than the heavier base layer bottoms that I use.

I'm not too sure about the body fat thing, unless you're underweight. I have, shall we say, quite ample hips, and that's where I get the coldest!

I hope this helps!

Since beginning the thought process to answer the OP, I have gotten colder and colder and now put on a down jacket in the house.

Think warm! :)

Wow, THANKS. Lots of useful replies.

Briefly, some more info:

* I have a Mountain Hardwear Phantom 15 down bag, temp rating is accurate according to research I've done, loft is still excellent, it's a women's bag and they put extra down in the foot area, and an excellent draft collar and hood. So, no sleeping bag complaints here.

* Always sleep in wool long undies (top and bottom), down jacket inside bag over top of torso, wool neckwarmer, wool cap, clean/dry underwear. I don't wear something if it is damp/wet.

* Nighttime regime for feet includes two pairs of dry wool socks plus Sierra Designs down booties inside my sleeping bag. I hate having to use those throw-away toe warmers. Will try more insulation under my feet, and/or hot water bottles.

* Yes it is true that my sleeping pads have been inadequate; that is the next area of investigation.

* I'm average body fat for a female, maybe ~24% right now, so not skinny, though I did notice I was even colder when down at 18% BF

* I do already employ all the "stay-warm" tricks; my girlfriends and I have already figured these out over the years! Namely: Clean/wash my feet *right* when I get into camp and then change into warm clothes *right away* before anything else; don't stay up late as it gets colder and colder; do use hot food & tea; sit on insulation (closed-cell foam pads) while in camp; jumping jacks right before getting into bed.

Now, some more questions based on your feedback:

* Love the idea of making a hot water bottle for my feet. Two questions: Can I do that in a Platypus or do I need hard plastic? And: does boiling nightly "feet water" increase fuel use substantially? We do make tea nearly nightly as it is…

* Never heard of those Warmlite tents. Interesting website. Why are the Warmlite tents warmer than, say, my Tarptent? What is it that makes tents warmer? Is it the double wall? Or the fuller wind protection? Or…? (Honestly, my next tent purchase was going to be one of those Duomids, I've loved the Mids and the headroom…and I wonder if a Duomid would be slightly easier to batten down from the wind, compared to my Tarptent…my guess is that the Duomid wouldn't be warmer than my Tarptent, but at least, wouldn't be colder.)

* My wool cap is pretty thin; I'm thinking of getting one of those down balaclavas. Good idea? Seems like it'd be fantastic warmth per weight.

* Is there a good reason to abandon my wool for synthetics, or supplement with synthetics? I LOVE my wool (no body odor; regulates temps well; never clammy; warm when damp), but have also heard (maybe on this site??) that wool's warmth per weight is overstated, even when it's perfectly dry. Comments?

* I actually do own a windshirt (Marmot Driclime). Honestly it seems awfully bulky, so I've used it for dayhikes but have been reluctant to throw it into the backpacking gear. But, if it really does offer a huge amount of warmth for that bulk, I'd reconsider.

Elizabeth

My windshirt is also Marmot, but was discontinued apparently – it weighs only 3 oz and folds away into a small pocket. It's just a very light, water resistant polyester zippered jacket minus a hood.

There is this – http://www.golite.com/Product/ProdDetail.aspx?p=209002110 for 3 oz as well.

the Wisp is on sale over here – http://www.zombierunner.com/store/product2173.html#2173

I'm going to make myself a down beanie and mittens, but really like the look of http://sectionhiker.com/2009/10/02/black-rock-gear-ul-down-hat/

Especially in the cold, slow the pace a half mile or maybe more from camp, so you are not overheated or sweaty when you arrive. Chilled sweat keeps you cold.

Andy, I never thought of this: "A tent might actually keep you colder if moisture builds up inside."

Leaving a door open, or switching to a tarp might help. A good airflow prevents condensation.

I've noticed that once I start to get tired, my metabolism comes to a grinding halt and I get chilled regardless of the ambient temperature. Drafts drive me crazy, and my feet and ears scream cold the loudest. Thanks for the info you've all shared.

Can anyone vouch for the effectiveness of the Black Rock hat that Lori linked? I just found that site last night, and it looks great! Wouldn't mind a little Elmer Fuddness over the ears, actually…

Changing to a warmer sleeping pad will make a HUGE difference. Unfortunately the most warmth for the weight pads are closed cell foam, which is bulky. A thinlight pad over top of a Neo-Air has been a good choice for me, because as a side sleeper I like the thickness of the air mattress, and the thinlight adds a lot of warmth for the weight, plus I can fold it and use it as a sitpad (or use it unfolded for a lounging area). Having a warm sitpad will make a big difference in staying warm while sitting around camp.

I also really like the BPL Cocoon pants – they are as light as most mid-weight base layers, but incredibly warmer. I prefer the synthetic insulted pants over down, because pants can easily get wet from tall grass or leaves on bushes while I'm on a bathroom run. While some people seem to stay adequately warm in a jacket and shorts, I find it really helps me to keep my legs warm. If they get cold, I am cold all over.

As others have said, warm head wear makes a big difference too.

As far as wool versus synthetic, fleece is warmer per ounce than wool (and other synthetics), but I prefer wool base layers due to the odor resistance. I just can't stand the stench of synthetic base layers (even those only going on my stinky body for sleeping) after a day or two on the trail.

Are you rockin a cute warm beanie?

If not maybe look in to that.

Hi Elizabeth,

Yes, I use a duomid for 3 seasons. It's great for the open views etc in pleasant weather, but for the 4th season conditions, it's the warmlite!

Why is the warmlite warmer? Yes, double wall makes a difference and the inner surface of one of the wall layers is aluminised (or something like) so it has a measure of heat reflection.

It is sealed all around so you are in control of ventilation through the adjustable vents, so less wind chill penetration. In some conditions it pays to seek out a breezy site to keep ventilation up and condensation down. Not a problem in the UK where the majority of 'wild camping' is on open moorland or above the treeline, rather than in woodland areas.

I haven't done any measurements, but subjectively I do notice a difference between inside and outside temps in excess of anything else I've tried. I've spoken to other users who say they get away with lighter bags with the warmlite too.

> Are you rockin a cute warm beanie?
> If not maybe look in to that.

+1 !

Cheers