Sleeping System

Part of Recommended Outdoor Gear by Mark Verber

A sleeping system is the combination of

• insulation above: including insulation Amount & Type / Quilts / Three Season / Winter
• something under you to provide comfort and insulation:  Foam Pads / Self Inflating / Air Mattresses / Hammocks / Cots / Pillows
• shelter: (now moved to it's own page).

Elsewhere I have some general notes about Getting a Good Night Sleep in the Outdoors which talks more about factors to concern and useful techniques.

Insulation Above: Sleeping Bags, Quilts, Etc

More than any other piece of gear, you typically get what you pay for when it comes to sleeping bags.

Amount of Insulation: There are a variety of factors which should be considered when selecting a how much insulation you want.  First you need to figure out what the lowest temperature you expect to face is.  Next you should consider if you are a "warm" sleeper or a "cold" sleeper.  For example, the same sleeping bag which keeps me toasty warm at 30F, leaves my wife chilled in 50F weather!  You should also consider what might supplement your bags warmth: tents keep you approx 5-15F degrees warmer than the outside, bivy sacks can add 5-15F, liners can add 4-8F, and wearing cloths or outerwear can help hugely.  Don't believe the silliness that sleeping bags work best when you aren't wearing clothing.  The problem with wearing clothing inside a sleeping bag is driven by two issues: moisture in damp clothing can sap your warmth, and too many cloths in a tight fitting bag will compress the insulation in the sleeping bag making it less efficient.  It should also be noted that many manufacturers reporting high optimistic temperature ratings for their sleeping bags.  The exception to this rule seems to companies that make high quality bags such as Marmot, Nukatak, Montbell, and Feathered Friends.  Western Mountaineering is the one company which seems to consistently under rates their sleeping bags.  The "inches of loft" is a much better predictor of how warm the bag will be than most companies "temperature ratings".  According to testing done by the US army, the average person wants needs following loft to keep warm enough to be safe while sleeping. Typically sleeping bag manufacturers report inches of loft in counting both the loft from the bottom of the bag and the top of the bag, so you need to divide by two to compare to this chart. Most people will want more loft than is listed by the army. Nearly everyone agrees that Western Mountaineering bags are accurately (for people who sleep cold) or conservatively (for normal people) rated:

There is a nice write up about the newer European rating system EN 13537 in Sleeping Well by Mammut.  I think this article has a lot of good information, but I think they are wrong about the effect of radiation in heat loss.  According to medical articles, in windless conditions a larger percent of your heat is lost via radiation.

Type of Insulation: The second factor you should consider is what sort of insulation you would like to use.  Historically the three best choices are Down, Polarguard (especially 3D and Delta), and Primaloft, though Climashield sounds pretty good and will likely replace Polarguard as the most commonly use synthetic in the next few years. Each of these materials has different performance characteristics.  You will need to decide the relative weighting of these characteristics to determine what insulation material will be the best for you.  Down is "rated" in terms of "fill power", that is the number of cubic inches one pound  will fill.  High fill power down has more down and less quills. There is a master's thesis about a model of how down compresses. I would recommend staying away from any synthetics materials which are not Polarguard, Climashield or Primaloft since they will tend to be heavier for the same warmth and will will be less compressible.  You might be interested in a message explaining why the Cocoon jacket switched from Primaloft to Polarguard Delta.  The following table gives you a sense of what 30F bags would be like using different insulation:

The are many factors that should be considered besides warmth / weight including durability, drape, and what techniques need to be used to stability the insulation. There is an interesting thread on BPL about the interplay of warmth, weight, and loft and R values and loft. The following is the best number I have found about the clo/oz numbers for a number of synthetics fills. 

• Polarguard 3D, .63 clo/oz
• Polarguard Delta, .68 clo/oz.
• Climashield HL, .68 clo/oz.
• Primaloft Sport, .74 clo/oz.
• Climashield Combat, .79 clo/oz.
• Climashield XP .82 clo/oz.
• Primaloft One as .84 clo/oz

There is a fair amount of controversy about how important of "warm when wet" is for a sleeping bag.  If down gets wet, it's going to take time to dry (hints drying down), and you are going to be cold. I used to think the getting down wet from splashing or rain was an issue, but then I realized that in 30 years of camping, my sleeping bag or quilt has gotten wet enough to significantly impact the performance of  a down bag once. There have been several times when the shell has gotten damp, but I was able to dry it out enough in the field that it wasn't a significant issue.  I also realized that my dad had been using the same down sleeping bag for almost 25 years.  It's not quite as lofty as it was originally, but it's still usable. I switched to using a down bag in 2000, and am very happy for the change.  There are some situations when I would consider a synthetic insulation: an extended trip in a location that has continuous, very damp conditions (so a bag could never dry out) and the temperature was around freezing. If I was spending most of my time in locations in week+ long trips which were cool-cold and damp (say western Washington state) I would consider switching back to synthetic insulation.  In conditions that were consistently cold (say below 0F) I would  use a down bag with a vapor barrier.... see the section below entitled "Suggestions for Winter Insulation".

Styles:  Sleeping bags are the most common way people stay warm in the back country.  Sleeping bags come in a variety of shapes and styles.  Most common among backpackers is the so call mummy bag.  Mummy style bags are popular because the they minimize weight by having little wasted material and by providing a good seal around the head and shoulders to prevent heat from leaking out.  Mummy bags typically list the shoulder girth which often varies from 55"-70".  I have found that 61-63" is the best for me as a 180lb 5'10" male.  Ideally there should have enough room to allow you to move as much as you need to be comfortable, but no more than necessary to minimize how much space you need to heat up and to minimize convection.  If you clothing is part of your sleeping system, you should make sure there is enough room for you to where those cloths without compressing your insulation. Rectangular bags are popular with some because they can be converted to a quilt and they provide a lot of room to move around.  Top-bags have mesh or fabric bottoms with all the insulation on the top of the bag, relying on a sleeping pad to provide insulation.  The theory is that you are going to crush any insulation which is under you, so why carry it around with you.  Increasingly popular with ultra-light backpackers are insulation filled blankets and specially design quilts with foot pockets.  Finally there are half bags, sometimes called elephant foot bags which are popular with climbers such as the Nunatak Akula. These looking like sleeping bags, but only cover the legs and are used in conjunction with an ultra warm jacket and hood to keep their upper body warm.

My Choice: I normally use a Nunatak Ghost Blanket which weights a mere 16 oz as the core my insulation. In warm weather I lay the quilt loosely over my body.  As the temperature drops I tighten the straps on the bottom of the quilt to block drafts, and add clothing as needed. When I am just on the edge I will curl up, pull my head under the quilt. I am comfortable using this quilt down to 30F when wearing a down balaclava, a light weight base layer, and wool socks.  In colder weather I have been comfortable my adding  my insulated vest, and primaloft socks.  If I am expecting the night time temperature to be consistently below 30F then I sometimes switch to a Western Mountaineering Versalite. If I only wanted one bag I would ebay my Ghost and Versalite and replace them with a Nunatak Arc Alpinist.  I haven't done this because my two bags system give me a lighter solution much of the year, keeps me warm in the coldest conditions I face, and provides me a bag I can loan to friends.

Three Season Sleeping Bags: As noted above there are a variety factors which can effect what sort of sleeping bag you might select. In most cases I would recommend against getting the warmest sleeping bag you can find since in most conditions you will be carrying unnecessary weight and you run the risk of overheating at night. I believe most people will be very well served by getting a light-weight mummy bag or quilt which will keep them warm enough down to 15-30 F.  This will keep you comfortable for most conditions, and safe in in all but the most extreme conditions. When facing the occasional colder conditions, it is possible to expand the temperature range with the use of clothing, a bivy, liner, etc. I recommend the Western Mountaineering Ultralight if it's not too tight for your shoulders or AlpinLite for you want a bit more room, a bag from Feathered Friends Light Flight line, Montbell UL SS Down Hugger #2/#3, or the Marmot Hydrogen if you don't mind a half zipper.  Other good choices include the 15F Marmot Helium and other Western Mountaineering Extremlite line bags.  I personally like sleeping bags which don't have side baffles except for bag for extreme cold.  This lets me shift more (or less) on the insulation to the top of the sleeping bag making it more or less insulating depending on the weather.  If you use a bag in a more narrow range of conditions having side baffles can be helpful because they prevent cold spots caused by down shifting. Rock&Ice did a brief but decent write-up on summer-ish 1 pound sleeping options. [They missed the most excellent SummerLite which just was released by Western Mountaineering.  35F bag, 59" shoulders, 1lb 3oz.] A nice Comparative Lightweight Sleeping Bag Review was done by Charles Lindsey a few years ago which list other high quality bags which I don't have personal experience using.  One family of bags that I would add to Charles' list would be the Montbell Down Hugger line. I am not really up on current synthetic filled sleeping bags but it seems that the North Face Cat's Meow and Integral Design Primaloft bags are the standard which synthetic bags are measured against.

Quilts: While I am a quilt fan, I would note that quilts are not a magic bullet. Several year ago high quality down quilts provided a significant warmth for weight advantage over commercially made sleeping bags of the day. Quilt lovers would say that sleeping bag have un-needed insulation and fabric.  You will compact the insulation under you rendering it nearly useless. A quilt puts the insulation were it will do the most good, on top of you.  Rather, rely on your sleeping pad to provide insulation. A quilt uses less fabric because it doesn't need to go around your body. A quilt doesn't need a zipper. The quilt is variable girth so you can wear all your clothing for added insulation under the quilt without compressing your insulation. See... it has to be lighter. Today though, there are several ultra high quality sleeping bags which are quite close to the weight for warmth of a quilt such as the WM Summerlite because of their close fit and insulation around the head and neck which a quilt lacks. In most cases though, a quilt will still have a warmth for weight advantage over a sleeping bag which is between 3-12oz depending on sleeping bag design provided you have a warm hat or drape the quilt over your head. On several shorter trips when it was surprisingly cold I pulled my head under the quilt which have quite a boast in how warm I felt. On a longer trip I would have worried about the moisture from my breath condensing in the insulation... but several experienced outdoors people have indicated they have done this an never had a significant problem. The second reason some people like quilts is that they feel more free and less constrained. In particular, it is easier to ventilate in warmer weather. Note: some mummy shape quilts like the Nunatak Arc Alpinist have a fairly long foot box which makes it hard to ventilate the legs in warm weather.  It is possible to use the sleeping bags with full length zippers in a quilt like fashion, getting close to a quilt experience. Some people think quilts are inappropriate in colder conditions because it's harder to prevent all drafts, and the colder it gets, the more the drafts will impact comfort. I have found quilts work fine in colder conditions. First, a shelter system which might include a bivy can provide protection from winds. Additionally, quilt users are typically wearing high loft clothing as part of their sleep system which provides a second barrier against drafts. Furthermore, a clothing + clothing strategy typically results in an easier transition because you are already in warm clothing.  Finally, quilts are simple, so they use less material, are less likely to fail, and are easier / cheaper to make. There are some downsides of a quilt. First, they are more prone to drafts than a typical sleeping bag. So a sleeping bag will be warmer for weight when used by an extremely restless sleeper on in the face of high winds. These effects can be significantly mitigated by using a bivy with a quilt. The downside of this combination is that a quilt + bivy tends to give up the weight advantage and  the freedom of movement that many people like in a quilt. On the other hand, the combination of a DWR bivy and a quilt provide a great deal of flexibility and allow the user to face a wide range of conditions. Personally, I don't use a bivy. When in situations where I would need protection from wind to stay sufficiently warm, I bring a shelter that can provide adequate wind protection plus I have found that since I don't move a lot at night and use the straps on the bottom of my quilt, drafts are pretty well sealed off, even in the face of wind and an open tarp. Also possible downside with using a quilt is that you will be sleeping directly on a pad, which typically isn't breathable. Some people find this unpleasant. Some people say you can't be a side sleeper with a quilt. I haven't had a significant problem. I would say that side sleeping reduces the temps I am comfortable by maybe 5F.. but that's mostly because the fill on my quilt is slightly lighter than I think is ideal so my hip makes a cold spot.  In cooler weather the Nunatak Arc Alpinist seems to be favored quilt.  In 2008 the GoLite Ultra Bag should be release which looks very nice. In mild weather there seem to be a number of popular quilts. Nunatak Ghost Blanket was one of the first, but it's a bit pricy. JacksRBetter also makes some nice looking quilts which are reasonably priced given their quality and versatility.  A number of the JacksRBetter quilts have features which let you wear then quilt in addition to using it to sleep under. Some people appreciate how this multi-use aspect often removes the need to bring any insulating clothing. I prefer a more minimalist quilt and a synthetic vest because I think it gives me a bit more versatility at the same weight. Fanatic Fringe Quilt, a 1.5lb synthetic quilt rated to 40F, is a reasonable $129.  Speer Hammocks makes a number of quilts (40F down for $139) as well as an interesting bag which surrounds a hammock called the PeaPod.  Other quilts are sold by Kick Ass Quilts and Mountain Laurel Designs. Some people open up sleeping bags and use them as quilts for one or two people.  Making a primaloft insulated backpacking quilt is  pretty easy.  A bit more work would be something like Jeremy Padgett down quilt or the ray-way quilt.

Couples Together: Couples often want to be able to sleep together. The most common approach is to have two sleeping bags which use the same zipper, with one bag having a left zip, and the other bag having a right zip. Another option to use a single sleeping bag with a Sweetie Pie Bag Doubler. Some rectangle sleeping bags come with an optional "undersheet" which turn them into a "top bag" which fits two.  Finally, some couples like to use two person quilts such as the Nunatak backcountry blanket. If a couple sleep close together, say spooned,  they should be comfortable in temperatures which are 10-15F colder than they would be comfortable in under the same insulation without someone else.

Other Options: There are a number of sleeping bags which don't have insulation on the bottom which are a cross between quilts and classic sleeping bags. I would look at the Western Mountaineering Pod (my favorite), Gossamer Gear SleepLight, Rab Q200 top bag, and a number of the bags from Big Agnes.  There are also some sleeping bags which can be opened up, zip in a bag extender, and then used as a two person bag. There are a number of bags which have been designed to be both outerwear and a sleeping bag including the Exped Wallcreeper, Nunatak Raku, and the Speer Hammock Frog Sac.

Suggestions of Winter Insulation: In the winter it is almost a given that the dew point for your night-time perspiration will be somewhere inside your sleeping bag since there is a large temperature gradient being warm on the inside and below freeze at the shell.  As a result your insulation will accumulate moisture. Down bags are find  for a few nights but then you will find their performance dropping as they lose loft. Synthetics bags are better a maintaining loft as the accumulate moisture from condensation, but they to will lose loft over time. Typically the most effective solution to this problem is to use a vapor barrier.  A vapor barrier is a waterproof layer which is placed between your body and your insulation which prevents you perspiration from entering your insulation and helps keep your skin moist. Your skin wants to be in approx 78% humidity and will perspiration to try and retain this.  You can use specially designed liner bags, wear vapor barrier clothing, or use a sleeping bag such as those from WarmLite which has  an integrated vapor barrier. Since you are protecting your bag from internal moisture, I would recommend using a highly protective external shell made from eVENT or DryLoft because you want maximum protection for your insulation and the vapor barrier will protect the insulation from condensation. Companies that make good cold weather down bags include Western Mountaineering,  Feathered Friends, Valandre, Marmot, Montbell, and Warmlite. PHD Mountain Software lets you specify your bag through a web based application. This is kind of cool, but Feather Friends will produce down bags to your specifications as well. There are a few options besides using a hard core winter sleeping bag. If you are wearing high loft outwear, you might consider making them part of your sleeping system. That way you can use a lighter weight sleeping bag provided it has enough room inside to prevent compressing the insulation of your garments, a quilt, or maybe a 1/2 bag for your legs. You could also consider using an overbag, or an insulated liner combined with whatever you use in milder conditions.

Kids: For kids I would recommend the Big Agnes Little Red sleeping bag for kids less than 4ft, and the The North Face Tigger for kids under 5ft.  Kids that are over 5ft should look at normal sleeping bags. The Montbell Super Stretch bags are well worth a look because they provide a range of widths in the same bag, and have a drawstring that lets you shorten the bag and let let the bag out when a long length is required.

Low Cost: Both Kelty Lightyear 3D and the Campmor "20F" Down Mummy can often been found for less than $100.  These are value priced sleeping bags, though I think they should be rated for more 35F rather than 20F.  For less than $100 you can make a high quality quilt. See my homemake page for links or check out the ray-way synthetic quilt or the thru-hiker down quilt kit.

What's Under You?

The next question is what to sleep on.  The first reason that people bring sleeping pads is to improve their sleeping comfort. I think getting a good night sleep, especially on an extended trip is very important. There is nothing worse than waking up in the morning feeling worse than when you went to bed. Some people can sleep on the bare ground or maybe 1/8" foam pads for some insulation. I wish I could do that for the weight and volumes savings, but I can't.  When I have tried more minimalist padding, not only have I not slept well, but in some cases I woke up with new aches which continues for several days (my hips in particular).  I have heard people assert that after a few days on the trail you will be able to sleep without a lot of padding because you have worn yourself out. This is not the case in my personal experience. There is an even more important reason to consider taking some sort of pad... and that's to stay warm. Sleeping bags insulation is compressed by your body weight which means that it provides almost no insulation.  If you don't have a pad, your body will try to warm what's below you.  If the air temperature is high but the ground is cool, this might be nice.. but in most conditions you want insulation below you. The amount of insulation you need will vary depending on the air temperature, ground temperature, and what sort of "ground" you are sleeping on. For example, if you are in the mountains, sleeping on a large chunk of granite, you will find that the rock is a very effective heat sink, while if you are in a pine forest with lots of needles and soft earth below you, you need little or no insulation because the needles are taking care of you. Since different people require different amounts of insulation, I think it is most useful to talk about the "R" values of pads rather than what temperature a pad is good down to. Below are a list of full size pads sorted by warmth / weight:

Therm-a-Rest has long dominated the marketplace, but Pacific Outdoor Equipment and Big Agnes are trying to challenge them.  No matter what type of pad you select you need to decide the shape and length of the pad.  Personally I like pads which are mummy shaped because the weight savings.  Except in the cold weather, when you need maximum insulation, I would recommend 3/4 length pad.  Most people don't put a lot of weight on their lower legs when they sleep so there is no need for the extra weight of a long pad.  If you can't live without padding for your lower legs, extend your pad using a stuff sack filled with soft items like extra cloth or your backpack.  Some people use torso sized pads to save even more weight.

My Choice: I use a Big Agnes Insulated AirCore (2.5 inch thick primaloft filled air mattress)  most of the year.  It is the lightest sleeping mat which permits me to get a good night sleep. When the temp is going to be below 20F (or I am sleeping on snow) I combine this with a foam pad for extra insulation. On super ultralight  trips I use a combination of a balloonbed (my review) and a GG thinlight foam pad. Both of these systems will be replaced by the Therm-a-Rest NeoAir if it is as good as reported. If I did a lot more snow camping I would pick up a Warmlite DAM.

Air Mattresses: Good quality backpacking air mattresses are lighter and more compact than self inflating pads for equivalent comfort / thickness.  Of course if your air mattress is punctured, you have no padding, where a self inflating pad has at least a bit of padding. On the other hand, you can use them as rafts when crossing rivers. Typical air mattresses are not very insulating.  As a result they shouldn't be used below 50F. In colder weather there a down or synthetic filled air mattresses can be ideal to provide comfort and warmth. For most people I recommend synthetic filled air mattresses.  They weight slightly more than self inflating pads, but they are warmer, pack smaller, and I think are more comfortable. For three season use (temp above 20F) I would recommend thet Pacific Outdoor Equipment (POE)  Ether Thermo (which replaced the previous max-thermo) and the Big Agnes (BA) Insulated AirCore. Both lines come in a variety of lengths and in both mummy and rectangular shapes. You won't go wrong with either one. I find the BA's larger number of air chambers (8 to POE's 6) makes a flatter and more comfortable sleeping surface. The BA Insulated AirCore had a run of failures a number of years ago where the Primaloft clumped producing cold spots.  BA replaced the failed pads but some people have been weary since then.  I have used my BA pad since 2003 and am delighted with it.  On the other hand, the POE is reported to be more insulated (we didn't notice a difference with the older version of the POE and I haven't heard any reports of failure in the field. My daughter is happy with her POE pad. For the environmentally conscious who want to put their money where there mouth is, there is the POE Eco Thermo which is nearly 3x the cost, but is manufacturers with eco friendly techniques and sustainable materials. During the summer you can flip the pad over so the insulation in by the ground rather than young to keep cool. In winter conditions I would recommend the Warmlite Down Air Mattress which offers nearly 2x the warmth / weight of self inflators, and has the best warmth / weight ratio of any pad except those using aerogel insulation. There are other down air mattresses such as the Exped Down Air Mattress, but they are heavier than the Warmlite DAM.  The lightest commercial un-insulated pad is the Big Agnes Clearview Air Pad which should be as light as 11oz for a 3/4 length pad. The lightest way get get an air mattress is to use balloons such as the the commercial balloonbed (my review) or make your own cheer-stick pad or a ultra-light poly-tube air mattress.  herm-a-Rest is suppose to ship a new pad called the NeoAir in 2009. Reports are that it is weights ~13oz and is warm down to around 20F.

Foam Pads:  These days, most foam pads are closed-cell foam because they don't soak up water, low cost, durability, and provide decent insulation.  Ultralight backpackers often like to use foam pads because they can become part of the suspension system for frameless backpacks and they can be trimmed down to save weight. In the winter, foam pads are often used during the day: as standing pads to help keep feet warm, or sitting pads which help keep the user warm and dry. The cheapest form are the "blue pads" which you can find almost anywhere (from WalMart to REI) which cost less than $10.  Ultra-light packers often trim this pads down to so that it is only as large as their torso or purchase torso size pads.  Slightly more comfortable is Cascade Designs' RidgeRest.  Cascade Design also makes the convenient folding Z-rest which has the unfortunate tendency to wear out with just moderate use.  I think the best foam pad are made from Evazote such as those sold by Gossamer Gear. Years ago, the Mt Washington Evazote pads were a cult favorite among the ultralight community, but they are no longer made. If you don't need padding, just a bit of insulate for your three-season trips, I would suggest picking up a ThinLight pad. Insul Mats by Pacific Outdoor Equipment have a number of innovative designs such as the Uber-lite for minimalist and a number of interesting hybrid pads, including foam & aerogel  POE Hyper High Mountain which is the warmest (R20!) pad made... if you believe the manufacturer's numbers.

Self Inflating Pads:  There are a variety of these out these days.  Montbell selling a self inflating pad which is thicker, lighter, and with better features than the therm-a-rest prolite 3 in Japan... hopefully they will start importing it into the US. In the US today, Cascade Design still makes the best self inflating pads.  Designed specifically for light-weight backpacking in moderate weather are the minimalist Cascade Design Pro 3 and the Pacific Outdoor max-Lite.  Both are lighter than the old Therm-a-Rest Ultralight.  For colder weather (or more sleeping comfort) is the slightly heavier Cascade Designs Pro 4 and the Pacific Outdoor max-Mountain.  Both these companies made a number of other pads which are larger, thicker and heavier.

Hammocks: In warm weather nothing will keep you as cool as a nice hammock.  In locations with trees it is typically easier to find a good location to hang a hammock than an ideal spot for a tent or tarp. When you are worried about ground water, what could be better than being suspended several feet above what concerns you. See my hammocks section in my shelters page for more information.

Pillows: One of the most common approaches is to place extra clothing (which is pretty soft) into your sleeping bag stuff sack. The downside of this is that the stuff sacks might not be the most comfortable thing against your face. Therm-a-rest makes stuff sacks which have a light fleece sewn into them which can be more comfortable than a nylon only stuff sack. Some people bring inflatable pillows. One of the light options for an air pillow are made by FlexAir (buy in limited quantities as the bpl.com ultralight pillow).  Some people will even take a small down or primaloft stuff pillows such as those made by Quixote.

Cots: Typically large and heavy.  LuxuryLite Low Rise Cot is only 30oz and packs up smaller than many pads... but it is $175. I have no experience with how comfortable it is.

Low Cost: A cheap closed cell foam pad.  The "blue" pads can be found many places for less than $10.