Warm Nights and A Lighter Pack, Wherever, Whenever
Use it as part of your sleeping gear and you can cut your bag weight dramatically, maybe in half, and still be warm.Here’s an actual example from the high Himalayas:
Sleep system used at top camp on broad peak and equivalent bags (all rated for -32°C) PACKWEIGHTSleep System:Hispar Overbag + Xero Down Suit 820g*Traditional single bag:Hispar 800 1290gTraditional single bag:Diamir 900 1740g* Xero Down Suit worn during the day.And another actual example from Scotland: SLEEP SYSTEM USED ON ISLE OF ARRAN AND EQUIVALENT BAG RATED FOR 2°C PACKWEIGHTSleep System:Ultra Bag + Wafer top, trousers & socks 375g*Traditional single bag:PHD lightweight 'Design Your Own' sleeping bag 550g* Wafer jacket and trousers worn during the day.
One main sleeping bag plus down clothing (or a Filler or Overbag) means multiple options from the same kit.
Sleep Systems offers new possibilities in so many situations as Sam Cook describes in this case study.
One light bag can cover a temperature range which would normally call for 3 different bags:
SLEEP SYSTEMS SEPARATE SLEEPING BAGS Scotland -5°C Hispar 400 bag Hispar 400 bag Everest Base Camp -15°C Hispar 400 bag + Ultra clothing Hispar 500 bag Aconcagua -25°C Hispar 400 bag + Hispar clothing Diamir 900 bag
And see how an overbag doesn't just double your options, it trebles them.
Stowability is a real plus for kayakers and bikers as well as campers and climbers.
Find out more how Martin Rickard used a PHD sleep system on a kayak expedition to Greenland.
Use it as part of your sleeping gear and you can cut your bag weight dramatically, maybe in half, and still be warm.
Does carrying a lighter bag mean sacrificing comfort and even a degree of safety? Not at all. Put together a good system and you can have all the benefits including comfort and safety.
It’s definitely more comfortable to have your down jacket on already when you get up on a cold morning. And in more serious situations is it safer to be faced with climbing out of your big bag and struggling into your down gear when the storm starts to take your tent apart? Or is it better to be ready simply to get up and deal with it?
Sleep Systems for Comfort:
- This Case Study shows how Sleep Systems is an ultralight way to add comfort to a standard sleeping bag when needed.
- This Case Study shows how Sleep Systems clothing adds comfort in camp.
Sleep Systems for Safety:
- This Case Study describes how, when sleeping at -21°C, Peter Hutchinson found that down clothing boosted his ultralight bag overnight, but also kept him warm when he had to move around.
- This Case Study explains how Sleep Systems allowed Martin Rickard to pack two small bags that could be stowed separately to prevent wetting while kayaking.
New dimensions for an old idea
Smart lightweight campers have been using their clothes to boost the warmth of their sleeping bags for years and climbers do it when they have to. Yet most of us are still carrying bags much bulkier and heavier than we need.
Now PHD Sleep Systems opens a whole new level of possibilities. It links together the unique warmth/weight performance of all our down gear along with the new designs we have created specifically to expand the potential of this powerful idea.
Sleep Systems lays it all out for you, a clear universal framework that works for any night outdoors anywhere, covering the whole range from valley camping to top camp on an 8000 metre peak.
Take a look and see how you can do a great deal more with less.
Recommended Sleep Systems
How Sleep Systems works
- Main Sleeping Bag
Naturally the main bag will be at the heart of your Sleep System. The six PHD bags we recommend all score 'best in the world' in warmth for weight, the perfect base to build your system on. All are fully customisable, including for width (an essential option for some systems). The basic ratings for these bags vary from +8°C for the Ultra to -21°C for the Hispar 600. They are all from the lightweight half of PHD’s sleeping bag range, but use them in combination with the other elements of Sleep Systems and they will keep you warm anywhere on earth.
- Main Sleeping Bag+ YOUR Clothing
Note about legs & feet: As this Case Study describes, it's important not to ignore your lower half. Cold legs or feet will stop you sleeping. So the clothing we recommend for Sleep Systems is a complete body set e.g. Minimus clothing means a Minimus jacket + down trousers & down socks -- and of course down trousers and socks have their own uses around camp. You can omit lower half items from your system, but the temperature ratings will not hold good if applied to only half the body.
- Main Sleeping Bag+ Jacket and Halfbag
This is an alternative system, which protects legs and feet with a simple halfbag (a short down bag coming up to the waist which overlaps with your jacket at the waist). A halfbag is an effective option and a useful item for a bivvy (intentional or not), but it doesn’t offer warmth on the move like down trousers. As this Case Study describes, you can of course omit lower half items from your system, but the temperature ratings will not hold good if applied to only half the body.
- Main Sleeping Bag+ Filler bag
The Filler bag is a PHD speciality we have developed over the last few years, the lightest form of booster for your main sleeping bag. Unlike Overbags the Filler bag works from the inside, filling the random airspaces inside the main bag and cutting out the convection currents. It's very light, very comfortable, and provides insulation for the whole body. The Filler bag will extend the performance of your main bag by about 10°C and is slightly more efficient than an Overbag (warmth for weight). These three Case Studies from Scotland, Wales, and Yorkshire Dales describe the Filler in action.
- Main Sleeping Bag+ Overbag
Overbags are the big guns in Sleep Systems. As the name says, they fit over your main bag and increase the warmth, most of them by well over 20°C. PHD have a lot of experience with overbags, having made them for polar travel, high mountains and winter camping for years. An overbag will convert your lightweight summer bag into a year round performer and give you a midway option too. For example the standalone rating for a Minimus bag is 5°C and for a Minim Combi overbag it’s -5°C. Put them together and the system will cope with -18°C. These three Case Studies from the high Himalayas, Scotland in Winter, and Greenland describe Overbags in action.
Plan Your Own System
Sleep Systems Technical Info
Temperature ratings: The standard ratings we quote for our sleeping bags are for night time. But our standard clothing ratings on the website are for daytime use and provide no guide to clothing performance when sleeping at night. So when different items are combined, all Sleep Systems ratings are adjusted to night time use. To clarify this point all the temperatures quoted for our Sleep Systems are called Full System Sleep Ratings. The usual rules about appropriate ground insulation apply.
The Full System Sleep Ratings quoted for various combinations of sleeping bag and clothing in our recommended Sleep Systems are as accurate as we can make them from experience, experiment, theory and test. We try to err consistently on the cautious side and to build in a small margin (see this Case Study when we tried Ultra/Minimus clothing inside a bag rated at -5°C in a Cold Store: that particular combination of clothing and bag was enough to provide a warm night right through at -21°C, but we have given it a rating of only -15°C in Sleep Systems).
However it's always worth taking your metabolism into account when putting together your own system. If your metabolism is 'average', the Full System Sleep Rating aims to give you a good night's sleep at that temperature under normal circumstances (see more information on our temperature ratings). If you sleep cold, it may be worth deliberately choosing a warmer combination than normal.
Also if your trip is going to be very long, remote or prone to stormy weather, it may be worth building an extra margin into your Sleep System gear choices to allow for these factors, as you would with any gear.
One of the real advantages of Sleep Systems is that you can put together such a variety of choice from a few pieces of kit that you should be able to cover a wide variation in conditions.
For a full picture see also 'Cautionary Tales', 'Widths', and 'Deterioration of Gear' in this Tech Info section.
Our Recommended Systems are ‘average’ collections which should suit most people. But we recognise that there will be those at both ends of the spectrum who may want something different. Experienced ultra-lightweight enthusiasts, whether racers or climbers, can sort out for themselves how far they want to trim the gear. While first-timers may find the idea of going to 8000 metres with a sleeping bag with only 600gm of down a bit daunting. At either end the decisions are yours, but we will be happy to help if we can.
Sleep Systems based on clothing provide warmth for the lower half of your body at the same insulation level as the named jacket or suit. These items are needed for the system to work – cold legs and feet make for poor sleep (see this Case Study). The lower-half options will usually be down trousers and socks or a halfbag. Halfbags are simpler and lighter, but don't offer double value as daytime wear like down trousers.
There are other activities when people camp. Long kayak trips and bike touring are two of them, which fall right into the area where Sleep Systems can be of real use. It's not just the overall weight reduction: even more important for both of these pursuits is the possibility of dividing your sleep gear into small packages rather than one big one (see this Case Study).
You may of course be doing something altogether different, something we haven't covered. If so, we'd be interested to hear of it and we'll do our best to advise you how to get the best value out of your sleep system.
The same rules apply to Sleep Systems as to any other gear. If you are going on a very long trip (North Pole) or a potentially cold damp one (Patagonia), where you can't stop to dry out your kit, then consider putting synthetic insulation into your mix. For example a Zeta Overbag as an outer might well pay off in those conditions, while it would be unnecessarily heavy as part of your system for most camps and climbs. Even Scottish winters may make synthetics worth a second look.
This is not strictly within the brief of technical info for Sleep Systems, but the following comments may be of use. Wet clothing always raises a new problem at night time, whether valley camping or on UK and other low/medium mountains. How to deal with it? In theory the best advice is don't get into this situation, but it can happen. So if it does, how does it affect our Sleep Systems ratings?
How wet are you? Drenched to the skin or just damp outer clothing?
a) Drenched: You shouldn't be drenched if your outer gear is up to the job, but assume it's happened. Tough call, especially if you've got more nights out to follow. You need the two basics - shelter, that is a tent or waterproof bivvy or even a cave or snowhole, and a dry sleeping bag: if you haven't got both of these, you could be in real trouble (forget our advice and survive).
With the basics you have two options.
- Sleep in all your clothing (wring it out first!): your base layer might dry out overnight, but the rest won't. Wet clothing is a poor insulator and you'll also be pushing moisture into the insulation of your sleeping bag by direct contact and evaporation. You'll have to reassess your situation the next day, taking into account the state of your gear.
- Probably the better option - sleep in just your base layer: less thickness, but you've got a fair chance of drying it off overnight. And if your sleeping bag has a water-resistant outer, you can wring out your outer gear and lay it over the top of the bag - it should add a little more warmth. As with the first option, reassess in the morning.
Sleep Systems: Our ratings do not apply to this situation. If your bag starts off dry, it should perform close to its normal TOT rating (evaporation from damp clothing will remove some warmth from the body), until it absorbs too much moisture.
Liners: See note below.**
b) Damp outer clothing: Same options as if you were drenched, but a much better starting point. Assess just how damp the layers are and wear anything reasonably dry. Anything beyond mildly damp, drape it over.
Sleep Systems: Our standard ratings do not apply even to damp clothing. A dry sleeping bag should perform close to it's normal TOT rating and should maintain that through most of the night as there will not be much moisture evaporating into the insulation. Naturally Primaloft clothing will come closer to full performance than down.
Liners: See note below.**
**Liners: A proofed bag liner will improve your situation. A VBL will add some warmth, but will not allow any evaporation, so any clothing inside will be just as wet in the morning. An Ultrashell liner is much lighter, will stop moisture transferring to your bag by direct contact, and will allow some drying inside overnight: overall probably a better bet.
For Sleep Systems which include thick down clothing, we have nominated a Wide main sleeping bag to enable the system to work properly. The extra width is needed to allow the clothing to loft (see this Case Study). If you are putting together your own system, all our Overbags are wide and the Minim, Hispar and Delta bags are all available as Wide or Extra Wide.
Note: If you would normally order a Wide sleeping bag for yourself, our advice about increased width to accommodate your clothing may mean that you will need an Extra Wide. If in doubt, contact us with your query and we'll try to help.
The temperature figures for Full System Sleep Ratings shown on the PHD website when combining items for a sleeping system are intended as a guide only to assist you in making your own choices. While they are as accurate as we can make them, it is impossible to cover all the variables. The combination of personal metabolism, food intake, ground insulation, humidity, and altitude are among the many factors which can seriously alter any rating. Accident or exceptional weather may also change the parameters of any venture. Personal experience is the best basis for your gear choices, coupled with expert advice on your venture when necessary.
Any failure of materials or workmanship is fully covered by PHD's standard lifetime guarantee alongside your statutory rights. However PHD accepts no responsibility for the suitability of combinations chosen by customers for their personal ventures.
Caution: On long Polar journeys or multi-bivouac siege routes sleeping gear may deteriorate and it is important allow for this and plan for it.
We have only included 6 of our PHD sleeping bags as the basis for our Recommended Sleep Systems. These are our core bags which offer the most efficient performance, with ratings ranging from +8°C down to -21°C as stand-alones. Sleep Systems transforms them into a range which will cover you for any temperature you want right down below -50°C.
You can customise the length and width of any of these bags. Add in the different zip and fabric options and you have hundreds of bags to choose from.
Self-built Systems: However if you already have different PHD gear or would prefer to buy items that are not shown, contact us with your query by phone or email and we'll do our best to advise you. We are unable to comment on gear from other manufacturers.
Comparisons between sleeping bag weights are shown in the Recommended Systems which feature clothing as the only ‘Plus’ item. These figures refer to the weight of your Main Sleeping Bag and nothing else. This allows a simple comparison with the weight of the single main bag you would have to carry to achieve the same temperature rating as that System (most of the bags used for this comparison are taken from the lightest and nearest equivalent on our Design-Your-Own sleeping bag site). Of course clothing also has a weight, but the clothing we quote is what you would normally take with you and use in the daytime on that kind of trip, whatever sleeping bag you choose to carry. So clothing is ignored in this calculation.
No weight comparisons are given for Systems featuring Filler, Overbags, or Halfbags as Plus items. The main value of these Systems is that they are extremely versatile and packable compared to a single big sleeping bag, and often carry an added safety margin. Also these items may or may not all be in your sac on different trips, which makes weight calculations complicated (See Case Study from Broad Peak when Ben Kane chose to sleep in his overbag and left his main bag behind!).
Clothing and Lower Halves: Sleep Systems based on clothing provide for warmth for the lower half of your body at the same insulation level as the named jacket or suit. The lower-half options will usually be down trousers and socks or a halfbag. Halfbags are simpler and lighter, but don’t offer double value as daytime wear, as down trousers do. These items are needed for the system to work -- cold legs and feet make for poor sleep (for example, see this Case Study).
Hoods and Hats: Hoods are an option for PHD’s lightest jackets and pullovers, Wafer, Ultra, Minimus, and Alpine Ultra. When selecting a sytem that includes one of these top halves, you will need the hood (or a down hat) to achieve the Full System Sleep Rating (for example, see this Case Study).